TY  - JOUR
A1  - Abdalla, H.
A1  - Adam, R.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arcaro, C.
A1  - Armand, C.
A1  - Armstrong, T.
A1  - Ashkar, H.
A1  - Backes, M.
A1  - Baghmanyan, V.
A1  - Martins, V. Barbosa
A1  - Barnacka, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Berge, D.
A1  - Bernlohr, K.
A1  - Bi, B.
A1  - Bottcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - de Lavergne, M. de Bony
A1  - Bordas, Pol
A1  - Breuhaus, M.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buchele, M.
A1  - Bulik, T.
A1  - Bylund, T.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Chand, T.
A1  - Chandra, S.
A1  - Chen, A.
A1  - Cotter, G.
A1  - Curylo, M.
A1  - Mbarubucyeye, J. Damascene
A1  - Davids, I. D.
A1  - Davies, J.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Dmytriiev, A.
A1  - Donath, A.
A1  - Doroshenko, V.
A1  - Duffy, C.
A1  - Dyks, J.
A1  - Egberts, Kathrin
A1  - Eichhorn, F.
A1  - Einecke, S.
A1  - Emery, G.
A1  - Ernenwein, J. -P.
A1  - Feijen, K.
A1  - Fegan, S.
A1  - Fiasson, A.
A1  - de Clairfontaine, G. Fichet
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Fussling, Matthias
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Giavitto, G.
A1  - Giunti, L.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M. -H.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hermann, G.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, T. L.
A1  - Holler, M.
A1  - Horbe, M.
A1  - Horns, D.
A1  - Huber, D.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jardin-Blicq, A.
A1  - Joshi, V.
A1  - Jung-Richardt, I.
A1  - Kasai, E.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katz, U.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - Klepser, S.
A1  - Kluzniak, W.
A1  - Komin, Nu.
A1  - Konno, R.
A1  - Kosack, K.
A1  - Kostunin, D.
A1  - Kreter, M.
A1  - Lamanna, G.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Levy, C.
A1  - Lohse, T.
A1  - Lypova, I.
A1  - Mackey, J.
A1  - Majumdar, J.
A1  - Malyshev, D.
A1  - Malyshev, D.
A1  - Marandon, V.
A1  - Marchegiani, P.
A1  - Marcowith, Alexandre
A1  - Mares, A.
A1  - Marti-Devesa, G.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitchell, A.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Montanari, A.
A1  - Moore, C.
A1  - Morris, P.
A1  - Moulin, Emmanuel
A1  - Muller, J.
A1  - Murach, T.
A1  - Nakashima, K.
A1  - Nayerhoda, A.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - O'Brien, Patrick
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Olivera-Nieto, L.
A1  - Wilhelmi, E. de Ona
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Panter, M.
A1  - Panny, S.
A1  - Parsons, R. D.
A1  - Peron, G.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V.
A1  - Noel, A. Priyana
A1  - Prokhorov, D. A.
A1  - Prokoph, H.
A1  - Puhlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reichherzer, P.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Remy, Q.
A1  - Renaud, M.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Ruiz-Velasco, E.
A1  - Sahakian, V.
A1  - Sailer, S.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Scalici, M.
A1  - Schussler, F.
A1  - Schutte, H. M.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Senniappan, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sinha, A.
A1  - Sol, H.
A1  - Specovius, A.
A1  - Spencer, S.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Sun, L.
A1  - Steenkamp, R.
A1  - Stegmann, C.
A1  - Steinmassl, S.
A1  - Steppa, C.
A1  - Takahashi, T.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Tomankova, L.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Volk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Watson, J.
A1  - Werner, F.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Wong, Yu Wun
A1  - Yusafzai, A.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zargaryan, D.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zhu, S. J.
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zouari, S.
A1  - Zywucka, N.
T1  - An extreme particle accelerator in the Galactic plane
BT  - HESS J1826-130
JF  - Astronomy and astrophysics : an international weekly journal
N2  - The unidentified very-high-energy (VHE; E > 0.1 TeV) gamma -ray source, HESS J1826-130, was discovered with the High Energy Stereoscopic System (HESS) in the Galactic plane. The analysis of 215 h of HESS data has revealed a steady gamma -ray flux from HESS J1826-130, which appears extended with a half-width of 0.21 degrees +/- 0.02 <br /> (stat)degrees <br /> stat degrees +/- 0.05 <br /> (sys)degrees sys degrees . The source spectrum is best fit with either a power-law function with a spectral index Gamma = 1.78 +/- 0.10(stat) +/- 0.20(sys) and an exponential cut-off at 15.2 <br /> (+5.5)(-3.2) -3.2+5.5 TeV, or a broken power-law with Gamma (1) = 1.96 +/- 0.06(stat) +/- 0.20(sys), Gamma (2) = 3.59 +/- 0.69(stat) +/- 0.20(sys) for energies below and above E-br = 11.2 +/- 2.7 TeV, respectively. The VHE flux from HESS J1826-130 is contaminated by the extended emission of the bright, nearby pulsar wind nebula, HESS J1825-137, particularly at the low end of the energy spectrum. Leptonic scenarios for the origin of HESS J1826-130 VHE emission related to PSR J1826-1256 are confronted by our spectral and morphological analysis. In a hadronic framework, taking into account the properties of dense gas regions surrounding HESS J1826-130, the source spectrum would imply an astrophysical object capable of accelerating the parent particle population up to greater than or similar to 200 TeV. Our results are also discussed in a multiwavelength context, accounting for both the presence of nearby supernova remnants, molecular clouds, and counterparts detected in radio, X-rays, and TeV energies.
KW  - ISM: supernova remnants
KW  - ISM: clouds
KW  - gamma rays: general
KW  - gamma rays:
KW  - ISM
Y1  - 2020
U6  - https://doi.org/10.1051/0004-6361/202038851
SN  - 0004-6361
SN  - 1432-0746
VL  - 644
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Akhperjanian, A. G.
A1  - Andersson, T.
A1  - Anguener, E. O.
A1  - Arakawa, M.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Carr, J.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Coffaro, M.
A1  - Colafrancesco, S.
A1  - Cologna, G.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Cui, Y.
A1  - Davids, I. D.
A1  - Decock, J.
A1  - Degrange, B.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gajdus, M.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Goyal, A.
A1  - Grondin, M. -H.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hervet, O.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, T. L.
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Janiak, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jogler, T.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Kolitzus, D.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Krueger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J. -P.
A1  - Lefaucheur, J.
A1  - Lefranc, V.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitche, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Oettl, S.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Richter, S.
A1  - Rieger, F.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Saito, S.
A1  - Salek, D.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schuessler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Settimo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spengler, G.
A1  - Spies, F.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Stycz, K.
A1  - Sushch, I.
A1  - Takahashi, T.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Wale, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zabalza, V.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zywucka, N.
A1  - Bamba, A.
A1  - Fukui, Y.
A1  - Sano, H.
A1  - Yoshiike, S.
T1  - A search for new supernova remnant shells in the Galactic plane with HESS
JF  - Astronomy and astrophysics : an international weekly journal
N2  - A search for new supernova remnants (SNRs) has been conducted using TeV gamma-ray data from the H.E.S.S. Galactic plane survey. As an identification criterion, shell morphologies that are characteristic for known resolved TeV SNRs have been used. Three new SNR candidates were identified in the H.E.S.S. data set with this method. Extensive multiwavelength searches for counterparts were conducted. A radio SNR candidate has been identified to be a counterpart to HESS J1534-571. The TeV source is therefore classified as a SNR. For the other two sources, HESS J1614-518 and HESS J1912 + 101, no identifying counterparts have been found, thus they remain SNR candidates for the time being. TeV-emitting SNRs are key objects in the context of identifying the accelerators of Galactic cosmic rays. The TeV emission of the relativistic particles in the new sources is examined in view of possible leptonic and hadronic emission scenarios, taking the current multiwavelength knowledge into account.
KW  - astroparticle physics
KW  - ISM: supernova remnants
KW  - cosmic rays
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201730737
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Akhperjanian, A. G.
A1  - Andersson, T.
A1  - Anguener, E. O.
A1  - Arakawa, M.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Carr, J.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Coffaro, M.
A1  - Colafrancesco, S.
A1  - Cologna, G.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Cui, Y.
A1  - Davids, I. D.
A1  - Decock, J.
A1  - Degrange, B.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Goyal, A.
A1  - Grondin, M. -H.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, T. L.
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Janiak, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jogler, T.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Kolitzus, D.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Krueger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J. -P.
A1  - Lefaucheur, J.
A1  - Lefranc, V.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Richter, S.
A1  - Rieger, F.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Saito, S.
A1  - Salek, D.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schuessler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Settimo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spengler, G.
A1  - Spies, F.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Stycz, K.
A1  - Sushch, I.
A1  - Takahashi, T.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venters, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zywucka, N.
T1  - Characterising the VHE diffuse emission in the central 200 parsecs of our Galaxy with HESS
JF  - Astronomy and astrophysics : an international weekly journal
N2  - The diffuse very high-energy (VHE; > 100 GeV) gamma-ray emission observed in the central 200 pc of the Milky Way by H.E.S.S. was found to follow dense matter distribution in the central molecular zone (CMZ) up to a longitudinal distance of about 130 pc to the Galactic centre (GC), where the flux rapidly decreases. This was initially interpreted as the result of a burst-like injection of energetic particles 104 yr ago, but a recent more sensitive H.E.S.S. analysis revealed that the cosmic-ray (CR) density profile drops with the distance to the centre, making data compatible with a steady cosmic PeVatron at the GC. In this paper, we extend this analysis to obtain, for the first time, a detailed characterisation of the correlation with matter and to search for additional features and individual gamma-ray sources in the inner 200 pc. Taking advantage of 250 h of H.E.S.S. data and improved analysis techniques, we perform a detailed morphology study of the diffuse VHE emission observed from the GC ridge and reconstruct its total spectrum. To test the various contributions to the total gamma-ray emission, we used an iterative 2D maximum-likelihood approach that allows us to build a phenomenological model of the emission by summing a number of different spatial components. We show that the emission correlated with dense matter covers the full CMZ and that its flux is about half the total diffuse emission flux. We also detect some emission at higher latitude that is likely produced by hadronic collisions of CRs in less dense regions of the GC interstellar medium. We detect an additional emission component centred on the GC and extending over about 15 pc that is consistent with the existence of a strong CR density gradient and confirms the presence of a CR accelerator at the very centre of our Galaxy. We show that the spectrum of full ridge diffuse emission is compatible with that previously derived from the central regions, suggesting that a single population of particles fills the entire CMZ. Finally, we report the discovery of a VHE gamma-ray source near the GC radio arc and argue that it is produced by the pulsar wind nebula candidate G0.13-0.11.
KW  - gamma rays: general
KW  - gamma rays: ISM
KW  - Galaxy: center
KW  - cosmic rays
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201730824
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Akhperjanian, A. G.
A1  - Andersson, T.
A1  - Anguener, E. O.
A1  - Arakawa, M.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Bilchele, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Carr, J.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chalme-Calvet, R.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Chretien, M.
A1  - Coffaro, M.
A1  - Colafrancesco, S.
A1  - Cologna, G.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Cui, Y.
A1  - Davids, I. D.
A1  - Decock, J.
A1  - Degrange, B.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gajdus, M.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Goya, A.
A1  - Grondin, M. -H.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hervet, O.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Janiak, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jogler, T.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - Kieffer, M.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Kolitzus, D.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Krueger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J. -P.
A1  - Lefaucheur, J.
A1  - Lefranc, V.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitche, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Oettl, S.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Arribas, M. Paz
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Richter, S.
A1  - Rieger, F.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Saito, S.
A1  - Salek, D.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schuessler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Settimo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spengler, G.
A1  - Spies, F.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Stycz, K.
A1  - Sushch, I.
A1  - Takahashi, T.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zabalza, V.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zywucka, N.
T1  - Deeper HESS observations of Vela Junior (RX J0852.0-4622)
BT  - Morphology studies and resolved spectroscopy
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Aims. We study gamma-ray emission from the shell-type supernova remnant (SNR) RXJ0852.0-4622 to better characterize its spectral properties and its distribution over the SNR. Methods. The analysis of an extended High Energy Spectroscopic System (H.E.S.S.) data set at very high energies (E > 100 GeV) permits detailed studies, as well as spatially resolved spectroscopy, of the morphology and spectrum of the whole RXJ0852.0-4622 region. The H.E.S.S. data are combined with archival data from other wavebands and interpreted in the framework of leptonic and hadronic models. The joint Fermi-LAT-H.E.S.S. spectrum allows the direct determination of the spectral characteristics of the parent particle population in leptonic and hadronic scenarios using only GeV-TeV data. Results. An updated analysis of the H.E.S.S. data shows that the spectrum of the entire SNR connects smoothly to the high-energy spectrum measured by Fermi-LAT. The increased data set makes it possible to demonstrate that the H.E.S.S. spectrum deviates significantly from a power law and is well described by both a curved power law and a power law with an exponential cutoff at an energy of E-cut = (6.7 +/- 1.2(stat) +/- 1.2(syst)) TeV. The joint Fermi-LAT-H.E.S.S. spectrum allows the unambiguous identification of the spectral shape as a power law with an exponential cutoff. No significant evidence is found for a variation of the spectral parameters across the SNR, suggesting similar conditions of particle acceleration across the remnant. A simple modeling using one particle population to model the SNR emission demonstrates that both leptonic and hadronic emission scenarios remain plausible. It is also shown that at least a part of the shell emission is likely due to the presence of a pulsar wind nebula around PSR J0855-4644.
KW  - astroparticle physics
KW  - gamma rays: general
KW  - acceleration of particles
KW  - cosmic rays
KW  - ISM: supernova remnants
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201630002
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Akhperjanian, A. G.
A1  - Andersson, T.
A1  - Anguener, E. O.
A1  - Arakawa, M.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Bottcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Carr, J.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chalme-Calvet, R.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Chretien, M.
A1  - Coffaro, M.
A1  - Colafrancesco, S.
A1  - Cologna, G.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Cui, Y.
A1  - Davids, I. D.
A1  - Decock, J.
A1  - Degrange, B.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gajdus, M.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Goyal, A.
A1  - Grondin, M. -H.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hervet, O.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Janiak, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jogler, T.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - Kieffer, M.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Kolitzus, D.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Kruger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J. -P.
A1  - Lefaucheur, J.
A1  - Lefranc, V.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Oettl, S.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Richter, S.
A1  - Rieger, F.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Saito, S.
A1  - Salek, D.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Settimo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spengler, G.
A1  - Spies, F.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian Michael
A1  - Stycz, K.
A1  - Sushch, I.
A1  - Takahashi, T.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zabalza, V.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zywucka, N.
T1  - Systematic search for very-high-energy gamma-ray emission from bow shocks of runaway stars
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. Runaway stars form bow shocks by ploughing through the interstellar medium at supersonic speeds and are promising sources of non-thermal emission of photons. One of these objects has been found to emit non-thermal radiation in the radio band. This triggered the development of theoretical models predicting non-thermal photons from radio up to very-high-energy (VHE, E >= 0.1 TeV) gamma rays. Subsequently, one bow shock was also detected in X-ray observations. However, the data did not allow discrimination between a hot thermal and a non-thermal origin. Further observations of different candidates at X-ray energies showed no evidence for emission at the position of the bow shocks either. A systematic search in the Fermi-LAT energy regime resulted in flux upper limits for 27 candidates listed in the E-BOSS catalogue. Aims. Here we perform the first systematic search for VHE gamma-ray emission from bow shocks of runaway stars. Methods. Using all available archival H.E.S.S. data we search for very-high-energy gamma-ray emission at the positions of bow shock candidates listed in the second E-BOSS catalogue release. Out of the 73 bow shock candidates in this catalogue, 32 have been observed with H.E.S.S. Results. None of the observed 32 bow shock candidates in this population study show significant emission in the H.E.S.S. energy range. Therefore, flux upper limits are calculated in five energy bins and the fraction of the kinetic wind power that is converted into VHE gamma rays is constrained. Conclusions. Emission from stellar bow shocks is not detected in the energy range between 0.14 and 18 TeV. The resulting upper limits constrain the level of VHE gamma-ray emission from these objects down to 0.1-1% of the kinetic wind energy.
KW  - radiation mechanisms: non-thermal
KW  - gamma rays: ISM
KW  - stars: early-type
KW  - gamma rays: stars
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201630151
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Akhperjanian, A. G.
A1  - Andersson, T.
A1  - Anguener, E. O.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Carr, J.
A1  - Carrigan, S.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chalme-Calvet, R.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Chretien, M.
A1  - Colafrancesco, S.
A1  - Cologna, G.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Couturier, C.
A1  - Cui, Y.
A1  - Davids, I. D.
A1  - Degrange, B.
A1  - Deil, C.
A1  - Devin, J.
A1  - dewilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dubus, G.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gajdus, M.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Goyal, A.
A1  - Grondin, M. -H.
A1  - Hadasch, D.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hervet, O.
A1  - Hillert, A.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Janiak, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jogler, T.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khelifi, B.
A1  - Kieffer, M.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Kolitzus, D.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Krayzel, F.
A1  - Krueger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J. -P.
A1  - Lefaucheur, J.
A1  - Lefranc, V.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - de Naurois, M.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Oettl, S.
A1  - Ohm, S.
A1  - Wilhelmi, E. de Ona
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Arribas, M. Paz
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Pita, S.
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Rieger, F.
A1  - Romoli, C.
A1  - Rosier-Lees, S.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Salek, D.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schuessler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Settimo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spengler, G.
A1  - Spies, F.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Stinzing, F.
A1  - Stycz, K.
A1  - Sushch, I.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - Valerius, K.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zabalza, V.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zywucka, N.
T1  - The population of TeV pulsar wind nebulae in the HESS Galactic Plane Survey
JF  - Astronomy and astrophysics : an international weekly journal
N2  - The nine-year H.E.S.S. Galactic Plane Survey (HGPS) has yielded the most uniform observation scan of the inner Milky Way in the TeV gamma-ray band to date. The sky maps and source catalogue of the HGPS allow for a systematic study of the population of TeV pulsar wind nebulae found throughout the last decade. To investigate the nature and evolution of pulsar wind nebulae, for the first time we also present several upper limits for regions around pulsars without a detected TeV wind nebula. Our data exhibit a correlation of TeV surface brightness with pulsar spindown power (E) over dot. This seems to be caused both by an increase of extension with decreasing (E) over dot, and hence with time, compatible with a power law R-PWN((E) over dot) similar to(E) over dot(0.65 +/- 0.20), and by a mild decrease of TeV gamma-ray luminosity with decreasing (E) over dot, compatible with L-1 (10 TeV) similar to (E) over dot(0.59 +/- 0.21). We also find that the off sets of pulsars with respect to the wind nebula centre with ages around 10 kyr are frequently larger than can be plausibly explained by pulsar proper motion and could be due to an asymmetric environment. In the present data, it seems that a large pulsar off set is correlated with a high apparent TeV efficiency L1- 10 TeV / (E) over dot. In addition to 14 HGPS sources considered firmly identified pulsar wind nebulae and 5 additional pulsar wind nebulae taken from literature, we find 10 HGPS sources that are likely TeV pulsar wind nebula candidates. Using a model that subsumes the present common understanding of the very high-energy radiative evolution of pulsar wind nebulae, we find that the trends and variations of the TeV observables and limits can be reproduced to a good level, drawing a consistent picture of present-day TeV data and theory.
KW  - gamma rays: general
KW  - catalogs
KW  - surveys
KW  - ISM: supernova remnants
KW  - pulsars: general
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201629377
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Akhperjanian, A. G.
A1  - Andersson, T.
A1  - Anguener, E. O.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Carr, J.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chalme-Calvet, R.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Chretien, M.
A1  - Colafrancesco, S.
A1  - Cologna, G.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Cui, Y.
A1  - Davids, I. D.
A1  - Decock, J.
A1  - Degrange, B.
A1  - Dei, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dubus, G.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Fukuyama, T.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gajdus, M.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Goyal, A.
A1  - Grondin, M. -H.
A1  - Hadasch, D.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hervet, O.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Janiak, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jogler, T.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khelifi, B.
A1  - Kieffer, M.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Kolitzus, D.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Krayzel, F.
A1  - Krueger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J. -P.
A1  - Lefaucheur, J.
A1  - Lefranc, V.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - de Naurois, M.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Oettl, S.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Rieger, F.
A1  - Romoli, C.
A1  - Rosier-Lees, S.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Salek, D.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schuessler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Settimo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanie, F.
A1  - Spengler, G.
A1  - Spies, F.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Stinzing, F.
A1  - Stycz, K.
A1  - Sushch, I.
A1  - Takahashi, T.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Edik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Volpe, F.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zabalza, V.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zywucka, N.
T1  - HESS observations of RX J1713.7-3946 with improved angular and spectral resolution
BT  - Evidence for gamma-ray emission extending beyond the X-ray emitting shell
JF  - Astronomy and astrophysics : an international weekly journal
KW  - acceleration of particles
KW  - cosmic rays
KW  - ISM: supernova remnants
KW  - gamma rays: general
KW  - astroparticle physic
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201629790
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Akhperjanian, A. G.
A1  - Andersson, T.
A1  - Anguener, O.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Carr, J.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chalme-Calvet, R.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Chretien, M.
A1  - Colafrancesco, S.
A1  - Cologna, G.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Cui, Y.
A1  - Davids, I. D.
A1  - Decock, J.
A1  - Degrange, B.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dubus, G.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gajdus, M.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Goyal, A.
A1  - Grondin, M. -H.
A1  - Hadasch, D.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hervet, O.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Janiak, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jogler, T.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khelifi, B.
A1  - Kieffer, M.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Kolitzus, D.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Krayzel, F.
A1  - Krueger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J. -P.
A1  - Lefaucheur, J.
A1  - Lefranc, V.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - de Naurois, M.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Oettl, S.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Rieger, F.
A1  - Romoli, C.
A1  - Rosier-Lees, S.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Salek, D.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schuessler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Settimo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spengler, G.
A1  - Spies, F.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Stinzing, F.
A1  - Stycz, K.
A1  - Sushch, I.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zabalza, V.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zywucka, N.
A1  - Katsuta, J.
T1  - The supernova remnant W49B as seen with HESS and Fermi-LAT
JF  - Astronomy and astrophysics : an international weekly journal
N2  - The supernova remnant (SNR) W49B originated from a core-collapse supernova that occurred between one and four thousand years ago, and subsequently evolved into a mixed-morphology remnant, which is interacting with molecular clouds (MC). Gamma-ray observations of SNR-MC associations are a powerful tool to constrain the origin of Galactic cosmic rays, as they can probe the acceleration of hadrons through their interaction with the surrounding medium and subsequent emission of non-thermal photons. We report the detection of a gamma-ray source coincident with W49B at very high energies (VHE; E > 100 GeV) with the H.E.S.S. Cherenkov telescopes together with a study of the source with five years of Fermi-LAT high-energy gamma-ray (0.06-300 GeV) data. The smoothly connected, combined source spectrum, measured from 60 MeV to multi-TeV energies, shows two significant spectral breaks at 304 +/- 20 MeV and 8.4(-2.5)(+2.5) GeV; the latter is constrained by the joint fit from the two instruments. The detected spectral features are similar to those observed in several other SNR-MC associations and are found to be indicative of gamma-ray emission produced through neutral-pion decay.
KW  - gamma rays: general
KW  - ISM: supernova remnants
KW  - ISM: clouds
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201527843
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Akhperjanian, A. G.
A1  - Anguenee, E. O.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Birsin, E.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Carr, J.
A1  - Casanova, Sabrina
A1  - Chadwick, P. M.
A1  - Chakraborty, N.
A1  - Chalme-Calvet, R.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Chretien, M.
A1  - Colafrancesco, S.
A1  - Cologna, G.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Couturier, C.
A1  - Cui, Y.
A1  - Davids, I. D.
A1  - Degrange, B.
A1  - Deil, C.
A1  - deWilt, P.
A1  - Dickinson, H. J.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dubus, G.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Dyrda, M.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gajdus, M.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Goya, A.
A1  - Grondin, M. -H.
A1  - Grudzinska, M.
A1  - Hadasch, D.
A1  - Hahn, J.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hervet, O.
A1  - Hillert, A.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Janiak, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jogler, T.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khelifi, B.
A1  - Kieffer, M.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Kolitzus, D.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Krayzel, F.
A1  - Krueger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J. -P.
A1  - Lefaucheur, J.
A1  - Lefranc, V.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lypova, I.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Menzler, U.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - de Naurois, M.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Oettl, S.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Arribas, M. Paz
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Pita, S.
A1  - Poona, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Rieger, F.
A1  - Romoli, C.
A1  - Rosier-Lees, S.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Salek, D.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schuessler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spengler, G.
A1  - Spies, F.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Stinzing, F.
A1  - Stycz, K.
A1  - Sushch, I.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tuffs, R.
A1  - van der Walt, J.
A1  - van Eldik, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venters, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zabalza, V.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zywucka, N.
T1  - A search for very high-energy flares from the microquasars GRS 1915+105, Circinus X-1, and V4641 Sgr using contemporaneous HESS and RXTE observations
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. Microquasars are potential gamma-ray emitters. Indications of transient episodes of gamma-ray emission were recently reported in at least two systems: Cyg X-1 and Cyg X-3. The identification of additional gamma-ray-emitting microquasars is required to better understand how gamma-ray emission can be produced in these systems. Aims. Theoretical models have predicted very high-energy (VHE) gamma-ray emission from microquasars during periods of transient outburst. Observations reported herein were undertaken with the objective of observing a broadband flaring event in the gamma-ray and X-ray bands. Methods. Contemporaneous observations of three microquasars, GRS 1915+105, Circinus X-1, and V4641 Sgr, were obtained using the High Energy Spectroscopic System (H.E.S.S.) telescope array and the Rossi X-ray Timing Explorer (RXTE) satellite. X-ray analyses for each microquasar were performed and VHE gamma-ray upper limits from contemporaneous H.E.S.S. observations were derived. Results. No significant gamma-ray signal has been detected in any of the three systems. The integral gamma-ray photon flux at the observational epochs is constrained to be I(>560 GeV) < 7.3 x 10(-13) cm(-2) S-1, I(>560 GeV) < 1.2 x 10-(12) cm s(-1), and I(>240 GeV) < 4.5 x 10(-12) cm(-2) s(-1) for GRS 1915+105, Circinus X-1, and V4641 Sgr, respectively. Conclusions. The gamma-ray upper limits obtained using H.E.S.S. are examined in the context of previous Cherenkov telescope observations of microquasars. The effect of intrinsic absorption is modelled for each target and found to have negligible impact on the flux of escaping gamma-rays. When combined with the X-ray behaviour observed using RXTE, the derived results indicate that if detectable VHE gamma-ray emission from microquasars is commonplace, then it is likely to be highly transient.
KW  - gamma rays: general
KW  - X-rays: binaries
KW  - X-rays: individuals: GRS 1915+105
KW  - X-rays: individuals: Circinus X-1
KW  - X-rays: individuals: V4641 Sgr
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201527773
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Akhperjanian, A. G.
A1  - Anguener, E. O.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Birsin, E.
A1  - Blackwell, R.
A1  - Bottcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Carr, J.
A1  - Casanova, Sabrina
A1  - Chakraborty, N.
A1  - Chalme-Calvet, R.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Chretien, M.
A1  - Colafrancesco, S.
A1  - Cologna, G.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Couturier, C.
A1  - Cui, Y.
A1  - Davids, I. D.
A1  - Degrange, B.
A1  - Deil, C.
A1  - deWilt, P.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dubus, G.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Dyrda, M.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gajdus, M.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Goyal, A.
A1  - Grondin, M. -H.
A1  - Grudzinska, M.
A1  - Hadasch, D.
A1  - Hahn, J.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hervet, O.
A1  - Hillert, A.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Janiak, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jogler, T.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khelifi, B.
A1  - Kieffer, M.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Kolitzus, D.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Krayzel, F.
A1  - Kruger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J. -P.
A1  - Lefaucheur, J.
A1  - Lefranc, V.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, E.
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lypova, I.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Menzler, U.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - de Naurois, M.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Oettl, S.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Arribas, M. Paz
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Pita, S.
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Rieger, F.
A1  - Romoli, C.
A1  - Rosier-Lees, S.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Salek, D.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spengler, G.
A1  - Spies, F.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Stinzing, F.
A1  - Stycz, K.
A1  - Sushch, I.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tuffs, R.
A1  - van der Walt, J.
A1  - van Eldik, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zabalza, V.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zywucka, N.
T1  - Extended VHE gamma-ray emission towards SGR1806-20, LBV 1806-20, and stellar cluster Cl*1806-20
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Using the High Energy Spectroscopic System (H.E.S.S.) telescopes we have discovered a steady and extended very high-energy (VHE) gamma-ray source towards the luminous blue variable candidate LBV 1806-20, massive stellar cluster Cl* 1806-20, and magnetar SGR 1806-20. The new VHE source, HESS J1808-204, was detected at a statistical significance of >6 sigma (post-trial) with a photon flux normalisation (2.9 +/- 0.4(stat) +/- 0.5(sys)) x 10(-13) ph cm(-2) s(-1) TeV-1 at 1 TeV and a power-law photon index of 2.3 +/- 0.2(stat) +/- 0.3(sys). The luminosity of this source (0.2 to 10 TeV; scaled to distance d = 8 : 7 kpc) is L-VHE similar to 1.6 x 10(34)(d = 8.7 kpc)(2) erg s(-1). The VHE gamma-ray emission is extended and is well fit by a single Gaussian with statistical standard deviation of 0.095 degrees +/- 0.015 degrees. This extension is similar to that of the synchrotron radio nebula G10.0-0.3, which is thought to be powered by LBV 1806-20. The VHE gamma-ray luminosity could be provided by the stellar wind luminosity of LBV 1806-20 by itself and/or the massive star members of Cl* 1806-20. Alternatively, magnetic dissipation (e.g. via reconnection) from SGR 1806-20 can potentially account for the VHE luminosity. The origin and hadronic and/or leptonic nature of the accelerated particles responsible for HESS J1808-204 is not yet clear. If associated with SGR 1806 20, the potentially young age of the magnetar (650 yr) can be used to infer the transport limits of these particles to match the VHE source size. This discovery provides new interest in the potential for high-energy particle acceleration from magnetars, massive stars, and/or stellar clusters.
KW  - gamma rays: general
KW  - stars: magnetars
KW  - stars: massive
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201628695
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Anguener, E. O.
A1  - Arakawa, M.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Colafrancesco, S.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Davids, I. D.
A1  - Decock, J.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Donath, A.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fernandez, D.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M. -H.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, T. L.
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Krueger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J. -P.
A1  - Lefaucheur, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Malyshev, D.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V.
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Safi-Harb, S.
A1  - Sahakian, V.
A1  - Saito, S.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schuessler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Settimo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Sushch, I.
A1  - Takahashi, T.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
T1  - Population study of Galactic supernova remnants at very high gamma-ray energies with HESS
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Shell-type supernova remnants (SNRs) are considered prime candidates for the acceleration of Galactic cosmic rays (CRs) up to the knee of the CR spectrum at E approximate to 3 x 10(15) eV. Our MilkyWay galaxy hosts more than 350 SNRs discovered at radio wavelengths and at high energies, of which 220 fall into the H.E.S.S. Galactic Plane Survey (HGPS) region. Of those, only 50 SNRs are coincident with a H.E.S.S source and in 8 cases the very high-energy (VHE) emission is firmly identified as an SNR. The H.E.S.S. GPS provides us with a legacy for SNR population study in VHE gamma-rays and we use this rich data set to extract VHE flux upper limits from all undetected SNRs. Overall, the derived flux upper limits are not in contradiction with the canonical CR paradigm. Assuming this paradigm holds true, we can constrain typical ambient density values around shell-type SNRs to n <= 7 cm(-3) and electron-to-proton energy fractions above 10 TeV to epsilon(ep) <= 5 x 10(-3). Furthermore, comparisons of VHE with radio luminosities in non-interacting SNRs reveal a behaviour that is in agreement with the theory of magnetic field amplification at shell-type SNRs.
KW  - gamma rays: general
KW  - ISM: supernova remnants
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201732125
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Anguener, E. O.
A1  - Arakawa, M.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Carrigan, S.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Colafrancesco, S.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Davids, I. D.
A1  - Decock, J.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Emery, G.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Gast, H.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M. -H.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, T. L.
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Krueger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J. -P.
A1  - Lefaucheur, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Marandon, V.
A1  - Malyshev, D.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Arribas, M. Paz
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V.
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Safi-Harb, S.
A1  - Sahakian, V.
A1  - Saito, S.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schandri, M.
A1  - Schlickeiser, R.
A1  - Schuessler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Settimo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Sushch, I.
A1  - Takahashi, T.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
T1  - The HESS Galactic plane survey
JF  - Astronomy and astrophysics : an international weekly journal
N2  - We present the results of the most comprehensive survey of the Galactic plane in very high-energy (VHE) gamma-rays, including a public release of Galactic sky maps, a catalog of VHE sources, and the discovery of 16 new sources of VHE gamma-rays. The High Energy Spectroscopic System (H.E.S.S.) Galactic plane survey (HGPS) was a decade-long observation program carried out by the H.E.S.S. I array of Cherenkov telescopes in Namibia from 2004 to 2013. The observations amount to nearly 2700 h of quality-selected data, covering the Galactic plane at longitudes from l = 250 degrees to 65 degrees and latitudes vertical bar b vertical bar <= 3 degrees. In addition to the unprecedented spatial coverage, the HGPS also features a relatively high angular resolution (0.08 degrees approximate to 5 arcmin mean point spread function 68% containment radius), sensitivity (less than or similar to 1.5% Crab flux for point-like sources), and energy range (0.2-100 TeV). We constructed a catalog of VHE gamma-ray sources from the HGPS data set with a systematic procedure for both source detection and characterization of morphology and spectrum. We present this likelihood-based method in detail, including the introduction of a model component to account for unresolved, large-scale emission along the Galactic plane. In total, the resulting HGPS catalog contains 78 VHE sources, of which 14 are not reanalyzed here, for example, due to their complex morphology, namely shell-like sources and the Galactic center region. Where possible, we provide a firm identification of the VHE source or plausible associations with sources in other astronomical catalogs. We also studied the characteristics of the VHE sources with source parameter distributions. 16 new sources were previously unknown or unpublished, and we individually discuss their identifications or possible associations. We firmly identified 31 sources as pulsar wind nebulae (PWNe), supernova remnants (SNRs), composite SNRs, or gamma-ray binaries. Among the 47 sources not yet identified, most of them (36) have possible associations with cataloged objects, notably PWNe and energetic pulsars that could power VHE PWNe.
KW  - gamma rays: general
KW  - surveys
KW  - Galaxy: general
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201732098
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, M.
A1  - Armand, C.
A1  - Arrieta, M.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Colafrancesco, S.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Davids, I. D.
A1  - Decock, J.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Donath, A.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M. -H.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, T. L.
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Kruger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lefaucheur, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Malyshev, D.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V.
A1  - Prokhorov, D. A.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Saito, S.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Sushch, I.
A1  - Takahashi, T.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
A1  - Enokiya, R.
A1  - Fukui, Y.
A1  - Hayakawa, T.
A1  - Okuda, T.
A1  - Torii, K.
A1  - Yamamoto, H.
T1  - HESS J1741-302: a hidden accelerator in the Galactic plane
JF  - Astronomy and astrophysics : an international weekly journal
N2  - The H.E.S.S. Collaboration has discovered a new very high energy (VHE, E > 0.1 TeV) gamma-ray source, HESS J1741-302, located in the Galactic plane. Despite several attempts to constrain its nature, no plausible counterpart has been found so far at X-ray and MeV/GeV gamma-ray energies, and the source remains unidentified. An analysis of 145-h of observations of HESS J1741-302 at VHEs has revealed a steady and relatively weak TeV source (similar to 1% of the Crab Nebula flux), with a spectral index of Gamma = 2.3 +/- 0.2(stat) +/- 0.2(sys), extending to energies up to 10 TeV without any clear signature of a cut-off. In a hadronic scenario, such a spectrum implies an object with particle acceleration up to energies of several hundred TeV. Contrary to most H.E.S.S. unidentified sources, the angular size of HESS J1741-302 is compatible with the H.E.S.S. point spread function at VHEs, with an extension constrained to be below 0.068 degrees at a 99% confidence level. The gamma-ray emission detected by H.E.S.S. can be explained both within a hadronic scenario, due to collisions of protons with energies of hundreds of TeV with dense molecular clouds, and in a leptonic scenario, as a relic pulsar wind nebula, possibly powered by the middle-aged (20 kyr) pulsar PSR B1737-30. A binary scenario, related to the compact radio source 1LC 358.266+0.038 found to be spatially coincident with the best fit position of HESS J1741-302, is also envisaged.
KW  - gamma rays: ISM
KW  - gamma rays: general
KW  - cosmic rays
KW  - ISM: clouds
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201730581
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, M.
A1  - Arrieta, M.
A1  - Aubert, P.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Bottcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Carr, J.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Colafrancesco, S.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Davids, I. D.
A1  - Decock, J.
A1  - Deil, C.
A1  - Devin, J.
A1  - Dewilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Emery, G.
A1  - Ernenwein, J-P
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M-H
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, T. L.
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Janiak, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jouvin, L.
A1  - Jung-Richardt, I
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Komin, Nu
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Krueger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lees, J-P
A1  - Lefaucheur, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J-P
A1  - Leser, Eva
A1  - Liu, R.
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Lopez-Coto, R.
A1  - Lypova, I
A1  - Malyshev, D.
A1  - Marandon, V
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P-O
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puelhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - De Los Reyes, R.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V
A1  - Saito, S.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schandri, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Settimo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Sushch, I
A1  - Takahashi, T.
A1  - Tavernet, J-P
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
T1  - Search for gamma-Ray Line Signals from Dark Matter Annihilations in the Inner Galactic Halo from 10 Years of Observations with HESS
JF  - Physical review letters
N2  - Spectral lines are among the most powerful signatures for dark matter (DM) annihilation searches in very-high-energy gamma rays. The central region of the Milky Way halo is one of the most promising targets given its large amount of DM and proximity to Earth. We report on a search for a monoenergetic spectral line from self-annihilations of DM particles in the energy range from 300 GeV to 70 TeV using a two-dimensional maximum likelihood method taking advantage of both the spectral and spatial features of the signal versus background. The analysis makes use of Galactic center observations accumulated over ten years (2004-2014) with the H.E.S.S. array of ground-based Cherenkov telescopes. No significant gamma-ray excess above the background is found. We derive upper limits on the annihilation cross section (sigma v) for monoenergetic DM lines at the level of 4 x 10(-28) cm(3) s(-1) at 1 TeV, assuming an Einasto DM profile for the Milky Way halo. For a DM mass of 1 TeV, they improve over the previous ones by a factor of 6. The present constraints are the strongest obtained so far for DM particles in the mass range 300 GeV-70 TeV. Ground-based gamma-ray observations have reached sufficient sensitivity to explore relevant velocity-averaged cross sections for DM annihilation into two gamma-ray photons at the level expected from the thermal relic density for TeV DM particles.
Y1  - 2018
U6  - https://doi.org/10.1103/PhysRevLett.120.201101
SN  - 0031-9007
SN  - 1079-7114
VL  - 120
IS  - 20
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Adam, R.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, M.
A1  - Arcaro, C.
A1  - Armand, C.
A1  - Ashkar, H.
A1  - Backes, M.
A1  - Martins, V. Barbosa
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Berge, D.
A1  - Bernloehr, K.
A1  - Bissaldi, E.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bregeon, J.
A1  - Breuhaus, M.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Bylund, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chand, T.
A1  - Chandra, S.
A1  - Chen, A.
A1  - Colafrancesco, S.
A1  - Curylo, M.
A1  - Davids, I. D.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Dmytriiev, A.
A1  - Donath, A.
A1  - Doroshenko, V
A1  - Dyks, J.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J-P
A1  - Eschbach, S.
A1  - Feijen, K.
A1  - Fegan, S.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Fussling, Matthias
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Giunti, L.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M-H
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, T. L.
A1  - Holler, M.
A1  - Horns, D.
A1  - Huber, D.
A1  - Iwasaki, H.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jardin-Blicq, A.
A1  - Jung-Richardt, I
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Kluzniak, W.
A1  - Komin, Nu
A1  - Kosack, K.
A1  - Kostunin, D.
A1  - Kreter, M.
A1  - Lamanna, G.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J-P
A1  - Leser, Eva
A1  - Levy, C.
A1  - Lohse, T.
A1  - Lypova, I
A1  - Mackey, J.
A1  - Majumdar, J.
A1  - Malyshev, D.
A1  - Marandon, V
A1  - Marcowith, Alexandre
A1  - Mares, A.
A1  - Mariaud, C.
A1  - Marti-Devesa, G.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Meintjes, P. J.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Moore, C.
A1  - Moulin, Emmanuel
A1  - Muller, J.
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Wilhelmi, E. de Ona
A1  - Ostrowski, M.
A1  - Oya, I
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Perennes, C.
A1  - Petrucci, P-O
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V
A1  - Noel, A. Priyana
A1  - Prokhorov, D. A.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Remy, Q.
A1  - Renaud, M.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Ruiz-Velasco, E.
A1  - Sahakian, V
A1  - Sailer, S.
A1  - Saito, S.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schutte, H. M.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Senniappan, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sinha, A.
A1  - Sol, H.
A1  - Specovius, A.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Takahashi, T.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Yang, R.
A1  - Yoneda, H.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
A1  - de Palma, F.
A1  - Axelsson, M.
A1  - Roberts, O. J.
T1  - A very-high-energy component deep in the gamma-ray burst afterglow
JF  - Nature : the international weekly journal of science
N2  - Gamma-ray bursts (GRBs) are brief flashes of gamma-rays and are considered to be the most energetic explosive phenomena in the Universe(1). The emission from GRBs comprises a short (typically tens of seconds) and bright prompt emission, followed by a much longer afterglow phase. During the afterglow phase, the shocked outflow-produced by the interaction between the ejected matter and the circumburst medium-slows down, and a gradual decrease in brightness is observed(2). GRBs typically emit most of their energy via.-rays with energies in the kiloelectronvolt-to-megaelectronvolt range, but a few photons with energies of tens of gigaelectronvolts have been detected by space-based instruments(3). However, the origins of such high-energy (above one gigaelectronvolt) photons and the presence of very-high-energy (more than 100 gigaelectronvolts) emission have remained elusive(4). Here we report observations of very-high-energy emission in the bright GRB 180720B deep in the GRB afterglow-ten hours after the end of the prompt emission phase, when the X-ray flux had already decayed by four orders of magnitude. Two possible explanations exist for the observed radiation: inverse Compton emission and synchrotron emission of ultrarelativistic electrons. Our observations show that the energy fluxes in the X-ray and gamma-ray range and their photon indices remain comparable to each other throughout the afterglow. This discovery places distinct constraints on the GRB environment for both emission mechanisms, with the inverse Compton explanation alleviating the particle energy requirements for the emission observed at late times. The late timing of this detection has consequences for the future observations of GRBs at the highest energies.
Y1  - 2019
U6  - https://doi.org/10.1038/s41586-019-1743-9
SN  - 0028-0836
SN  - 1476-4687
VL  - 575
IS  - 7783
SP  - 464
EP  - +
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Adam, R.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, M.
A1  - Arcaro, C.
A1  - Armand, C.
A1  - Ashkar, H.
A1  - Backes, M.
A1  - Martins, V. Barbosa
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Berge, D.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Böttcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bregeon, J.
A1  - Breuhaus, M.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Büchele, M.
A1  - Bulik, T.
A1  - Bylund, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chand, T.
A1  - Chandra, S.
A1  - Chen, A.
A1  - Colafrancesco, S.
A1  - Curylo, M.
A1  - Davids, I. D.
A1  - Deil, C.
A1  - Devin, J.
A1  - DeWilt, P.
A1  - Dirson, L.
A1  - Djannati-Ata, A.
A1  - Dmytriiev, A.
A1  - Donath, A.
A1  - Doroshenko, V
A1  - Dyks, J.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J-P
A1  - Eschbach, S.
A1  - Feijen, K.
A1  - Fegan, S.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Füßling, Matthias
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M-H
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, James Anthony
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, Tim Lukas
A1  - Holler, M.
A1  - Horns, D.
A1  - Huber, D.
A1  - Iwasaki, H.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jardin-Blicq, A.
A1  - Jung-Richardt, I
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Kluzniak, W.
A1  - Komin, Nu
A1  - Kosack, K.
A1  - Kostunin, D.
A1  - Kraus, M.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J-P
A1  - Leser, Eva
A1  - Levy, C.
A1  - Lohse, T.
A1  - Lypova, I
A1  - Mackey, J.
A1  - Majumdar, J.
A1  - Malyshev, D.
A1  - Marandon, V
A1  - Marcowith, Alexandre
A1  - Mares, A.
A1  - Mariaud, C.
A1  - Marti-Devesa, G.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Meintjes, P. J.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Moore, C.
A1  - Moulin, Emmanuel
A1  - Muller, J.
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Wilhelmi, E. de Ona
A1  - Ostrowski, M.
A1  - Oya, I
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Perennes, C.
A1  - Petrucci, P-O
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V
A1  - Priyana Noel, A.
A1  - Prokhorov, D. A.
A1  - Prokoph, H.
A1  - Pühlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Remy, Q.
A1  - Renaud, M.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Ruiz-Velasco, E.
A1  - Sahakian, V
A1  - Saito, S.
A1  - Sanchez, David M.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schüssler, F.
A1  - Schulz, A.
A1  - Schutte, H.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Senniappan, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sinha, A.
A1  - Sol, H.
A1  - Specovius, A.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Takahashi, T.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van Der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Yang, R.
A1  - Yoneda, H.
A1  - Zacharias, Michael
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
A1  - Meyer, M.
T1  - Constraints on the emission region of 3C 279 during strong flares in 2014 and 2015 through VHE gamma-ray observations with HESS
JF  - Astronomy and astrophysics : an international weekly journal
N2  - The flat spectrum radio quasar 3C 279 is known to exhibit pronounced variability in the high-energy (100MeV < E < 100 GeV) gamma-ray band, which is continuously monitored with Fermi-LAT. During two periods of high activity in April 2014 and June 2015 target-of-opportunity observations were undertaken with the High Energy Stereoscopic System (H.E.S.S.) in the very-high-energy (VHE, E > 100 GeV) gamma-ray domain. While the observation in 2014 provides an upper limit, the observation in 2015 results in a signal with 8 : 7 sigma significance above an energy threshold of 66 GeV. No VHE variability was detected during the 2015 observations. The VHE photon spectrum is soft and described by a power-law index of 4.2 +/- 0.3. The H.E.S.S. data along with a detailed and contemporaneous multiwavelength data set provide constraints on the physical parameters of the emission region. The minimum distance of the emission region from the central black hole was estimated using two plausible geometries of the broad-line region and three potential intrinsic spectra. The emission region is confidently placed at r greater than or similar to 1 : 7 X 1017 cm from the black hole, that is beyond the assumed distance of the broad-line region. Time-dependent leptonic and lepto-hadronic one-zone models were used to describe the evolution of the 2015 flare. Neither model can fully reproduce the observations, despite testing various parameter sets. Furthermore, the H.E.S.S. data were used to derive constraints on Lorentz invariance violation given the large redshift of 3C 279.
KW  - radiation mechanisms: non-thermal
KW  - quasars: individual: 3C 279
KW  - galaxies: active
KW  - relativistic processes
Y1  - 2019
U6  - https://doi.org/10.1051/0004-6361/201935704
SN  - 1432-0746
VL  - 627
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Adam, Remi
A1  - Aharonian, Felix A.
A1  - Benkhali, Faical Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, Masanori
A1  - Arcaro, C
A1  - Armand, Catherine
A1  - Armstrong, T.
A1  - Egberts, Kathrin
T1  - Very high energy γ-ray emission from two blazars of unknown redshift and upper limits on their distance
JF  - Monthly Notices of the Royal Astronomical Society
N2  - We report on the detection of very high energy (VHE; E > 100 GeV) gamma-ray emission from the BL Lac objects KUV 00311-1938 and PKS 1440-389 with the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observations were accompanied or preceded by multiwavelength observations with Fermi/LAT, XRT and UVOT onboard the Swift satellite, and ATOM. Based on an extrapolation of the Fermi/LAT spectrum towards the VHE gamma-ray regime, we deduce a 95 per cent confidence level upper limit on the unknown redshift of KUV 00311-1938 of z < 0.98 and of PKS 1440-389 of z < 0.53. When combined with previous spectroscopy results, the redshift of KUV 00311-1938 is constrained to 0.51 <= z < 0.98 and of PKS 1440-389 to 0.14 (sic) z < 0.53.
KW  - BL Lacertae objects: individual
KW  - galaxies: high-redshift
KW  - gamma-rays: general
KW  - Resolved and unresolved sources as a function of wavelength
Y1  - 2020
VL  - 494
IS  - 4
PB  - Wiley-Blackwell
CY  - Oxford
ER  - 
TY  - GEN
A1  - Abdalla, Hassan E.
A1  - Adam, Remi
A1  - Aharonian, Felix A.
A1  - Benkhali, Faical Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, Masanori
A1  - Arcaro, C
A1  - Armand, Catherine
A1  - Armstrong, T.
A1  - Egberts, Kathrin
T1  - Very high energy γ-ray emission from two blazars of unknown redshift and upper limits on their distance
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - We report on the detection of very high energy (VHE; E > 100 GeV) gamma-ray emission from the BL Lac objects KUV 00311-1938 and PKS 1440-389 with the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observations were accompanied or preceded by multiwavelength observations with Fermi/LAT, XRT and UVOT onboard the Swift satellite, and ATOM. Based on an extrapolation of the Fermi/LAT spectrum towards the VHE gamma-ray regime, we deduce a 95 per cent confidence level upper limit on the unknown redshift of KUV 00311-1938 of z < 0.98 and of PKS 1440-389 of z < 0.53. When combined with previous spectroscopy results, the redshift of KUV 00311-1938 is constrained to 0.51 <= z < 0.98 and of PKS 1440-389 to 0.14 (sic) z < 0.53.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1202 
KW  - BL Lacertae objects: individual
KW  - galaxies: high-redshift
KW  - gamma-rays: general
KW  - Resolved and unresolved sources as a function of wavelength
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-526000
SN  - 1866-8372
IS  - 4
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Aharonian, Felix A.
A1  - Ait Benkhali, Faical
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, M.
A1  - Arcaro, C.
A1  - Armand, C.
A1  - Arrieta, M.
A1  - Backes, Michael
A1  - Barnard, M.
A1  - Becherini, Yvonne
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernlöhr, Konrad
A1  - Blackwell, R.
A1  - Böttcher, Markus
A1  - Boisson, C.
A1  - Bolmont, Julien
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Büchele, M.
A1  - Bulik, Tomasz
A1  - Bylund, Tomas
A1  - Capasso, Massimo
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, Matteo
A1  - Chakraborty, Nachiketa
A1  - Chandra, S.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Colafrancesco, Sergio
A1  - Condon, B.
A1  - Davids, Isak
A1  - Deil, Christoph
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Dmytriiev, A.
A1  - Donath, Axel
A1  - Doroshenko, Victor
A1  - Dyks, J.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J. -P.
A1  - Eschbach, Stefan
A1  - Fegan, S.
A1  - Fiasson, Armand
A1  - Fontaine, G.
A1  - Funk, Sebastian
A1  - Füßling, Matthias
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Gate, F.
A1  - Giavitto, Gianluca
A1  - Eisenacher Glawion, Dorit
A1  - Glicenstein, Jean-François
A1  - Gottschall, D.
A1  - Grondin, Marie-Hélène
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Heinzelmann, G.
A1  - Henri, Gilles
A1  - Hermann, G.
A1  - Hinton, James Anthony
A1  - Hofmann, Werner
A1  - Hoischen, Clemens
A1  - Holch, Tim Lukas
A1  - Holler, M.
A1  - Horns, D.
A1  - Huber, D.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Jankowsky, David
A1  - Jankowsky, Felix
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzyński, Krzysztof
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Kluzniak, W.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Kruger, P. P.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lefaucheur, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Malyshev, D.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marti-Devesa, G.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Meintjes, P. J.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V.
A1  - Noel, A. Priyana
A1  - Prokhorov, D. A.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Ruiz-Velasco, E.
A1  - Sahakian, V.
A1  - Saito, S.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Senniappan, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sinha, A.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Specovius, A.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Takahashi, T.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Yang, R.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
A1  - Cirelli, M.
A1  - Panci, P.
A1  - Sala, F.
A1  - Silk, J.
A1  - Taoso, M.
T1  - Searches for gamma-ray lines and 'pure WIMP' spectra from Dark Matter annihilations in dwarf galaxies with H.E.S.S.
JF  - Journal of cosmology and astroparticle physics
N2  - Dwarf spheroidal galaxies are among the most promising targets for detecting signals of Dark Matter (DM) annihilations. The H.E.S.S. experiment has observed five of these systems for a total of about 130 hours. The data are re-analyzed here, and, in the absence of any detected signals, are interpreted in terms of limits on the DM annihilation cross section. Two scenarios are considered: i) DM annihilation into mono-energetic gamma-rays and ii) DM in the form of pure WIMP multiplets that, annihilating into all electroweak bosons, produce a distinctive gamma-ray spectral shape with a high-energy peak at the DM mass and a lower-energy continuum. For case i), upper limits at 95% confidence level of about <sigma upsilon > less than or similar to 3 x 10(-25) cm(3) s(-1) are obtained in the mass range of 400 GeV to 1TeV. For case ii), the full spectral shape of the models is used and several excluded regions are identified, but the thermal masses of the candidates are not robustly ruled out.
KW  - dark matter detectors
KW  - dark matter experiments
KW  - dwarfs galaxies
KW  - gamma ray detectors
Y1  - 2018
U6  - https://doi.org/10.1088/1475-7516/2018/11/037
SN  - 1475-7516
IS  - 11
PB  - IOP Publishing Ltd. (Bristol)
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Anguener, E. O.
A1  - Arakawa, M.
A1  - Arcaro, C.
A1  - Armand, C.
A1  - Ashkar, H.
A1  - Backes, M.
A1  - Martins, V. Barbosa
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Berge, D.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bregeon, J.
A1  - Breuhaus, M.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Bylund, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chand, T.
A1  - Chandra, S.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Colafrancesco, S.
A1  - Curylo, M.
A1  - Davids, I. D.
A1  - Deil, C.
A1  - Devin, J.
A1  - de Wilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Dmytriiev, A.
A1  - Donath, A.
A1  - Doroshenko, V
A1  - Dyks, J.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J-p
A1  - Eschbach, S.
A1  - Feijen, K.
A1  - Fegan, S.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M-H
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, James Anthony
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, Tim Lukas
A1  - Holler, M.
A1  - Horns, D.
A1  - Huber, D.
A1  - Iwasaki, H.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jung-Richardt, I
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Kluzniak, W.
A1  - Komin, Nu
A1  - Kosack, K.
A1  - Kostunin, D.
A1  - Kraus, M.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J-P
A1  - Leser, Eva
A1  - Levy, C.
A1  - Lohse, T.
A1  - Lopez-Coto, R.
A1  - Lypova, I
A1  - Mackey, J.
A1  - Majumdar, J.
A1  - Malyshev, D.
A1  - Marandon, V
A1  - Marcowith, Alexandre
A1  - Mares, A.
A1  - Mariaud, C.
A1  - Marti-Devesa, G.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Meintjes, P. J.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Muller, J.
A1  - Moore, C.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Wilhelmi, E. de Ona
A1  - Ostrowski, M.
A1  - Oya, I
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Perennes, C.
A1  - Petrucci, P-O
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V
A1  - Noel, A. Priyana
A1  - Prokhorov, D. A.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Remy, Q.
A1  - Renaud, M.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Ruiz-Velasco, E.
A1  - Sahakian, V
A1  - Saito, S.
A1  - Sanchez, David M.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schutte, H.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Senniappan, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sinha, A.
A1  - Sol, H.
A1  - Specovius, A.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Takahashi, T.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Yang, R.
A1  - Yoneda, H.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
A1  - Maxted, N.
T1  - Upper limits on very-high-energy gamma-ray emission from core-collapse supernovae observed with H.E.S.S.
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Young core-collapse supernovae with dense-wind progenitors may be able to accelerate cosmic-ray hadrons beyond the knee of the cosmic-ray spectrum, and this may result in measurable gamma-ray emission. We searched for gamma-ray emission from ten super- novae observed with the High Energy Stereoscopic System (H.E.S.S.) within a year of the supernova event. Nine supernovae were observed serendipitously in the H.E.S.S. data collected between December 2003 and December 2014, with exposure times ranging from 1.4 to 53 h. In addition we observed SN 2016adj as a target of opportunity in February 2016 for 13 h. No significant gamma-ray emission has been detected for any of the objects, and upper limits on the >1 TeV gamma-ray flux of the order of similar to 10(-13) cm(-)(2)s(-1) are established, corresponding to upper limits on the luminosities in the range similar to 2 x 10(39) to similar to 1 x 10(42) erg s(-1). These values are used to place model-dependent constraints on the mass-loss rates of the progenitor stars, implying upper limits between similar to 2 x 10(-5) and similar to 2 x 10(-3) M-circle dot yr(-1) under reasonable assumptions on the particle acceleration parameters.
KW  - gamma rays: general
KW  - supernovae: general
KW  - cosmic rays
Y1  - 2019
U6  - https://doi.org/10.1051/0004-6361/201935242
SN  - 1432-0746
VL  - 626
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, M.
A1  - Arcaro, C.
A1  - Armand, C.
A1  - Arrieta, M.
A1  - Backes, M.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Bottcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Bylund, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chandra, S.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Colafrancesco, S.
A1  - Condon, B.
A1  - Davids, I. D.
A1  - Dei, C.
A1  - Devin, J.
A1  - dewilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Dmytriiev, A.
A1  - Donath, A.
A1  - Dyks, J.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J-P
A1  - Eschbach, S.
A1  - Fegan, S.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M-H
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, T. L.
A1  - Holler, M.
A1  - Horns, D.
A1  - Huber, D.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jouvin, L.
A1  - Jung-Richardt, I
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Kluzniak, W.
A1  - Komin, Nu
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Kruger, P. P.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lefaucheur, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J-P
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Lopez-Coto, R.
A1  - Lypova, I
A1  - Malyshev, D.
A1  - Marandon, V
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marti-Devesa, G.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Meintjes, P. J.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Perennes, C.
A1  - Petrucci, P-O
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V
A1  - Noel, A. Priyana
A1  - Prokhorov, D. A.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowel, G.
A1  - Rudak, B.
A1  - Ruiz-Velasco, E.
A1  - Sahakian, V
A1  - Saito, S.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Senniappan, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sinha, A.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Specovius, A.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Sushch, I
A1  - Takahashi, T.
A1  - Tavernet, J-P
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Woernlein, A.
A1  - Yang, R.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
T1  - The starburst galaxy NGC 253 revisited by HESS and Fermi-LAT
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. NGC 253 is one of only two starburst galaxies found to emit gamma-rays from hundreds of MeV to multi-TeV energies. Accurate measurements of the very-high-energy (VHE; E> 100 GeV) and high-energy (HE; E > 60 MeV) spectra are crucial to study the underlying particle accelerators, probe the dominant emission mechanism(s) and to study cosmic-ray interaction and transport. Aims. The measurement of the VHE gamma-ray emission of NGC 253 published in 2012 by H.E.S.S. was limited by large systematic uncertainties. Here, the most up to date measurement of the gamma-ray spectrum of NGC 253 is investigated in both HE and VHE gamma-rays. Assuming a hadronic origin of the gamma-ray emission, the measurement uncertainties are propagated into the interpretation of the accelerated particle population. Methods. The data of H.E.S.S. observations are reanalysed using an updated calibration and analysis chain. The improved Fermi-LAT analysis employs more than 8 yr of data processed using pass 8. The cosmic-ray particle population is evaluated from the combined HE-VHE gamma-ray spectrum using NAIMA in the optically thin case. Results. The VHE gamma-ray energy spectrum is best fit by a power-law distribution with a flux normalisation of (1.34 +/- 0.14(stat) +/- 0.27(sys)) x 10(-13) cm(-2) s(-1) TeV-1 at 1 TeV - about 40% above, but compatible with the value obtained in Abramowski et al. (2012). The spectral index Gamma = 2.39 +/- 0.14(stat) +/- 0.25(sys) is slightly softer than but consistent with the previous measurement within systematic errors. In the Fermi energy range an integral flux of F(E > 60 MeV) = (1.56 +/- 0.28(stat) +/- 0.15(sys)) x 10(-8) cm(-2) s(-1) is obtained. At energies above similar to 3 GeV the HE spectrum is consistent with a power-law ranging into the VHE part of the spectrum measured by H.E.S.S. with an overall spectral index Gamma = 2.22 +/- 0.06(stat). Conclusions. Two scenarios for the starburst nucleus are tested, in which the gas in the starburst nucleus acts as either a thin or a thick target for hadronic cosmic rays accelerated by the individual sources in the nucleus. In these two models, the level to which NGC 253 acts as a calorimeter is estimated to a range of f(cal) = 0.1 to 1 while accounting for the measurement uncertainties. The presented spectrum is likely to remain the most accurate measurements until the Cherenkov Telescope Array (CTA) has collected a substantial set of data towards NGC 253.
KW  - astroparticle physics
KW  - galaxies: starburst
KW  - gamma rays: galaxies
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201833202
SN  - 1432-0746
VL  - 617
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, M.
A1  - Arcaro, C.
A1  - Armand, C.
A1  - Arrieta, M.
A1  - Backes, M.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Bottcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Bylund, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chandra, S.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Colafrancesco, S.
A1  - Condon, B.
A1  - Davids, I. D.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Dmytriiev, A.
A1  - Donath, A.
A1  - Doroshenko, V
A1  - Dyks, J.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J-P
A1  - Eschbach, S.
A1  - Fegan, S.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M-H
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, James Anthony
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, Tim Lukas
A1  - Holler, M.
A1  - Horns, D.
A1  - Huber, D.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jouvin, L.
A1  - Jung-Richardt, I
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Kluzniak, W.
A1  - Komin, Nu
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Kruger, P. P.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lefaucheur, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J-P
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Lopez-Coto, R.
A1  - Lypova, I
A1  - Malyshev, D.
A1  - Marandon, V
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marti-Devesa, G.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Meintjes, P. J.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Perennes, C.
A1  - Petrucci, P-O
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V
A1  - Noel, A. Priyana
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Ruiz-Velasco, E.
A1  - Sahakian, V
A1  - Saito, S.
A1  - Sanchez, David M.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Senniappan, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sinha, A.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Specovius, A.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Takahashi, T.
A1  - Tavernet, J-P
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Yang, R.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
T1  - The 2014TeV gamma-Ray Flare of Mrk 501 Seen with HESS
BT  - Temporal and Spectral Constraints on Lorentz Invariance Violation
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - The blazar Mrk 501 (z = 0.034) was observed at very-high-energy (VHE, E greater than or similar to 100 GeV) gamma-ray wavelengths during a bright flare on the night of 2014 June 23-24 (MJD 56832) with the H.E.S.S. phase-II array of Cherenkov telescopes. Data taken that night by H.E.S.S. at large zenith angle reveal an exceptional number of gamma-ray photons at multi-TeV energies, with rapid flux variability and an energy coverage extending significantly up to 20 TeV. This data set is used to constrain Lorentz invariance violation (LIV) using two independent channels: a temporal approach considers the possibility of an energy dependence in the arrival time of gamma-rays, whereas a spectral approach considers the possibility of modifications to the interaction of VHE gamma-rays with extragalactic background light (EBL) photons. The non-detection of energy-dependent time delays and the non-observation of deviations between the measured spectrum and that of a supposed power-law intrinsic spectrum with standard EBL attenuation are used independently to derive strong constraints on the energy scale of LIV (E-QG) in the subluminal scenario for linear and quadratic perturbations in the dispersion relation of photons. For the case of linear perturbations, the 95% confidence level limits obtained are E-QG,E-1 > 3.6 x 10(17) GeV using the temporal approach and E-QG,E-1 > 2.6 x 10(19) GeV using the spectral approach. For the case of quadratic perturbations, the limits obtained are E-QG,E-2 > 8.5 x 10(10) GeV using the temporal approach and E-QG,E-2 > 7.8 x 10(11) GeV using the spectral approach.
KW  - astroparticle physics
KW  - BL Lacertae objects: individual (Mrk 501)
KW  - gamma rays: galaxies
Y1  - 2019
U6  - https://doi.org/10.3847/1538-4357/aaf1c4
SN  - 0004-637X
SN  - 1538-4357
VL  - 870
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, M.
A1  - Arcaro, C.
A1  - Armand, C.
A1  - Arrieta, M.
A1  - Backes, M.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Bottcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buchele, M.
A1  - Bulik, T.
A1  - Bylund, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chand, T.
A1  - Chandra, S.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Colafrancesco, S.
A1  - Condon, B.
A1  - Davids, I. D.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Dmytriiev, A.
A1  - Donath, A.
A1  - Doroshenko, V.
A1  - Dyks, J.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Fegan, S.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M. -H.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, James Anthony
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, Tim Lukas
A1  - Holler, M.
A1  - Horns, D.
A1  - Huber, D.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Kluzniak, W.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Kraus, M.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lefaucheur, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lopez-Coto, R.
A1  - Lorentz, M.
A1  - Lypova, I.
A1  - Malyshev, D.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marti-Devesa, G.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Meintjes, P. J.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Moore, C.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V.
A1  - Noel, A. Priyana
A1  - Prokhorov, D. A.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Ruiz-Velasco, E.
A1  - Sahakian, V.
A1  - Saito, S.
A1  - Sanchez, David M.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schutte, H.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Senniappan, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sinha, A.
A1  - Sol, H.
A1  - Specovius, A.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Takahashi, T.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Yang, R.
A1  - Yoneda, H.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
T1  - H.E.S.S. observations of the flaring gravitationally lensed galaxy PKS 1830-211
JF  - Monthly notices of the Royal Astronomical Society
N2  - PKS 1830-211 is a known macrolensed quasar located at a redshift of z = 2.5. Its highenergy gamma-ray emission has been detected with the Fermi-Large Area Telescope (LAT) instrument and evidence for lensing was obtained by several authors from its high-energy data. Observations of PKS 1830-211 were taken with the High Energy Stereoscopic System (H.E.S.S.) array of Imaging Atmospheric Cherenkov Telescopes in 2014 August, following a flare alert by the Fermi-LAT Collaboration. The H.E.S.S observations were aimed at detecting a gamma-ray flare delayed by 20-27 d from the alert flare, as expected from observations at other wavelengths. More than 12 h of good-quality data were taken with an analysis threshold of similar to 67 GeV. The significance of a potential signal is computed as a function of the date and the average significance over the whole period. Data are compared to simultaneous observations by Fermi-LAT. No photon excess or significant signal is detected. An upper limit on PKS 1830-211 flux above 67 GeV is computed and compared to the extrapolation of the Fermi-LAT flare spectrum.
KW  - gravitational lensing: strong
KW  - diffuse radiation
KW  - gamma-rays: galaxies
Y1  - 2019
U6  - https://doi.org/10.1093/mnras/stz1031
SN  - 0035-8711
SN  - 1365-2966
VL  - 486
IS  - 3
SP  - 3886
EP  - 3891
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, M.
A1  - Arcaro, C.
A1  - Armand, C.
A1  - Arrieta, M.
A1  - Backes, M.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Bottcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Bylund, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chand, T.
A1  - Chandra, S.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Colafrancesco, S.
A1  - Condon, B.
A1  - Davids, I. D.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Dmytriiev, A.
A1  - Donath, A.
A1  - Doroshenko, V
A1  - Dyks, J.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J-P
A1  - Eschbach, S.
A1  - Fegan, S.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M-H
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, James Anthony
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, Tim Lukas
A1  - Holler, M.
A1  - Horns, D.
A1  - Huber, D.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jouvin, L.
A1  - Jung-Richardt, I
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Kluzniak, W.
A1  - Komin, Nu
A1  - Kosack, K.
A1  - Kraus, M.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lefaucheur, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J-P
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lopez-Coto, R.
A1  - Lypova, I
A1  - Malyshev, D.
A1  - Marandon, V
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marti-Devesa, G.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Meintjes, P. J.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Moore, C.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Perennes, C.
A1  - Petrucci, P-O
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V
A1  - Noel, A. Priyana
A1  - Prokhorov, D. A.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Ruiz-Velasco, E.
A1  - Sahakian, V
A1  - Saito, S.
A1  - Sanchez, David M.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schutte, H.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Senniappan, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sinha, A.
A1  - Sol, H.
A1  - Specovius, A.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Takahashi, T.
A1  - Tavernet, J-P
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Yang, R.
A1  - Yoneda, H.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
T1  - Particle transport within the pulsar wind nebula HESS J1825-137
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. We present a detailed view of the pulsar wind nebula (PWN) HESS J1825-137. We aim to constrain the mechanisms dominating the particle transport within the nebula, accounting for its anomalously large size and spectral characteristics. Aims. The nebula was studied using a deep exposure from over 12 years of H.E.S.S. I operation, together with data from H.E.S.S. II that improve the low-energy sensitivity. Enhanced energy-dependent morphological and spatially resolved spectral analyses probe the very high energy (VHE, E > 0.1 TeV) gamma-ray properties of the nebula. Methods. The nebula emission is revealed to extend out to 1.5 degrees from the pulsar, similar to 1.5 times farther than previously seen, making HESS J1825-137, with an intrinsic diameter of similar to 100 pc, potentially the largest gamma-ray PWN currently known. Characterising the strongly energy-dependent morphology of the nebula enables us to constrain the particle transport mechanisms. A dependence of the nebula extent with energy of R proportional to E alpha with alpha = -0.29 +/- 0.04(stat) +/- 0.05(sys) disfavours a pure diffusion scenario for particle transport within the nebula. The total gamma-ray flux of the nebula above 1 TeV is found to be (1.12 +/- 0.03(stat) +/- 0.25(sys)) +/- 10(-11) cm(-2) s(-1), corresponding to similar to 64% of the flux of the Crab nebula. Results. HESS J1825-137 is a PWN with clearly energy-dependent morphology at VHE gamma-ray energies. This source is used as a laboratory to investigate particle transport within intermediate-age PWNe. Based on deep observations of this highly spatially extended PWN, we produce a spectral map of the region that provides insights into the spectral variation within the nebula.
KW  - gamma rays: general
KW  - acceleration of particles
KW  - convection
KW  - diffusion
KW  - pulsars: general
Y1  - 2019
U6  - https://doi.org/10.1051/0004-6361/201834335
SN  - 1432-0746
VL  - 621
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, M.
A1  - Arcaro, C.
A1  - Armand, C.
A1  - Backes, M.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Berge, D.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Bottcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Bylund, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chand, T.
A1  - Chandra, S.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Colafrancesco, S.
A1  - Condon, B.
A1  - Davids, I. D.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Dmytriiev, A.
A1  - Donath, A.
A1  - Doroshenko, V
A1  - Dyks, J.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J-P
A1  - Eschbach, S.
A1  - Feijen, K.
A1  - Fegan, S.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M-H
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, James Anthony
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, Tim Lukas
A1  - Holler, M.
A1  - Horns, D.
A1  - Huber, D.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jouvin, L.
A1  - Jung-Richardt, I
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Kluzniak, W.
A1  - Komin, Nu
A1  - Kosack, K.
A1  - Kostunin, D.
A1  - Kraus, M.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J-P
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lopez-Coto, R.
A1  - Lypova, I
A1  - Malyshev, D.
A1  - Marandon, V
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marti-Devesa, G.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Meintjes, P. J.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Moore, C.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Wilhelmi, E. de Ona
A1  - Ostrowski, M.
A1  - Oya, I
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Perennes, C.
A1  - Petrucci, P-O
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V
A1  - Noel, A. Priyana
A1  - Prokhorov, D. A.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Ruiz-Velasco, E.
A1  - Sahakian, V
A1  - Saito, S.
A1  - Sanchez, David M.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schutte, H.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Senniappan, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sinha, A.
A1  - Sol, H.
A1  - Specovius, A.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Takahashi, T.
A1  - Tavernet, J-P
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, Luigi
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Yang, R.
A1  - Yoneda, H.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
T1  - H.E.S.S. and Suzaku observations of the Vela X pulsar wind nebula
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. Pulsar wind nebulae (PWNe) represent the most prominent population of Galactic very-high-energy gamma-ray sources and are thought to be an efficient source of leptonic cosmic rays. Vela X is a nearby middle-aged PWN, which shows bright X-ray and TeV gamma-ray emission towards an elongated structure called the cocoon. Aims. Since TeV emission is likely inverse-Compton emission of electrons, predominantly from interactions with the cosmic microwave background, while X-ray emission is synchrotron radiation of the same electrons, we aim to derive the properties of the relativistic particles and of magnetic fields with minimal modelling. Methods. We used data from the Suzaku XIS to derive the spectra from three compact regions in Vela X covering distances from 0.3 to 4 pc from the pulsar along the cocoon. We obtained gamma-ray spectra of the same regions from H.E.S.S. observations and fitted a radiative model to the multi-wavelength spectra. Results. The TeV electron spectra and magnetic field strengths are consistent within the uncertainties for the three regions, with energy densities of the order 10(-12) erg cm(-3). The data indicate the presence of a cutoff in the electron spectrum at energies of similar to 100 TeV and a magnetic field strength of similar to 6 mu G. Constraints on the presence of turbulent magnetic fields are weak. Conclusions. The pressure of TeV electrons and magnetic fields in the cocoon is dynamically negligible, requiring the presence of another dominant pressure component to balance the pulsar wind at the termination shock. Sub-TeV electrons cannot completely account for the missing pressure, which may be provided either by relativistic ions or from mixing of the ejecta with the pulsar wind. The electron spectra are consistent with expectations from transport scenarios dominated either by advection via the reverse shock or by diffusion, but for the latter the role of radiative losses near the termination shock needs to be further investigated in the light of the measured cutoff energies. Constraints on turbulent magnetic fields and the shape of the electron cutoff can be improved by spectral measurements in the energy range greater than or similar to 10 keV.
KW  - stars: winds, outflows
KW  - gamma rays: stars
KW  - radiation mechanisms: non-thermal
KW  - acceleration of particles
KW  - pulsars: individual: PSR B0833-45
Y1  - 2019
U6  - https://doi.org/10.1051/0004-6361/201935458
SN  - 1432-0746
VL  - 627
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdalla, Hassan E.
A1  - Collaboration, H. E. S. S.
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Angüner, Ekrem Oǧuzhan
A1  - Arakawa, M.
A1  - Armand, C.
A1  - Arrieta, M.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Barnard, M.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Blackwell, R.
A1  - Bottcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bonnefoy, S.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Buechele, M.
A1  - Bulik, T.
A1  - Capasso, M.
A1  - Caroff, S.
A1  - Carosi, A.
A1  - Casanova, Sabrina
A1  - Cerruti, M.
A1  - Chakraborty, N.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Colafrancesco, S.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Davids, I. D.
A1  - Decock, J.
A1  - Deil, C.
A1  - Devin, J.
A1  - deWilt, P.
A1  - Dirson, L.
A1  - Djannati-Atai, A.
A1  - Donath, A.
A1  - Dyks, J.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Emery, G.
A1  - Ernenwein, J. -P.
A1  - Eschbach, S.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Fernandes, M. V.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Funk, S.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Gate, F.
A1  - Giavitto, G.
A1  - Glawion, D.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Grondin, M. -H.
A1  - Hahn, J.
A1  - Haupt, M.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hoischen, Clemens
A1  - Holch, T. L.
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Iwasaki, H.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Jankowsky, D.
A1  - Jankowsky, F.
A1  - Jingo, M.
A1  - Jouvin, L.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katsuragawa, M.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khangulyan, D.
A1  - Khelifi, B.
A1  - King, J.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Kraus, M.
A1  - Kruger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lefaucheur, J.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Leser, Eva
A1  - Lohse, T.
A1  - Lorentz, M.
A1  - Liu, R.
A1  - Lopez-Coto, R.
A1  - Lypova, I.
A1  - Malyshev, D.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mohrmann, L.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - Nakashima, S.
A1  - de Naurois, M.
A1  - Ndiyavala, H.
A1  - Niederwanger, F.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Ohm, S.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, M.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Perennes, C.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Piel, Q.
A1  - Pita, S.
A1  - Poireau, V.
A1  - Prokhorov, D. A.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Rauth, R.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Rieger, F.
A1  - Rinchiuso, L.
A1  - Romoli, C.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Saito, S.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schussler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seglar-Arroyo, M.
A1  - Seyffert, A. S.
A1  - Shafi, N.
A1  - Shilon, I.
A1  - Shiningayamwe, K.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spir-Jacob, M.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Steppa, Constantin Beverly
A1  - Sushch, I.
A1  - Takahashi, T.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tibaldo, L.
A1  - Tiziani, D.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tsirou, M.
A1  - Tsuji, N.
A1  - Tuffs, R.
A1  - Uchiyama, Y.
A1  - van der Walt, D. J.
A1  - van Eldik, C.
A1  - van Rensburg, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wadiasingh, Z.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zanin, R.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Ziegler, A.
A1  - Zorn, J.
A1  - Zywucka, N.
T1  - Detection of variable VHE gamma-ray emission from the extra-galactic gamma-ray binary LMC P3
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. Recently, the high-energy (HE, 0.1-100 GeV) gamma-ray emission from the object LMC P3 in the Large Magellanic Cloud (LMC) has been discovered to be modulated with a 10.3-day period, making it the first extra-galactic gamma-ray binary. Aims. This work aims at the detection of very-high-energy (VHE, >100 GeV) gamma-ray emission and the search for modulation of the VHE signal with the orbital period of the binary system. Methods. LMC P3 has been observed with the High Energy Stereoscopic System (H.E.S.S.); the acceptance-corrected exposure time is 100 h. The data set has been folded with the known orbital period of the system in order to test for variability of the emission. Results. VHE gamma-ray emission is detected with a statistical significance of 6.4 sigma. The data clearly show variability which is phase-locked to the orbital period of the system. Periodicity cannot be deduced from the H.E.S.S. data set alone. The orbit-averaged luminosity in the 1-10 TeV energy range is (1.4 +/- 0.2) x 10(35) erg s(-1). A luminosity of (5 +/- 1) x 10(35) erg s(-1) is reached during 20% of the orbit. HE and VHE gamma-ray emissions are anti-correlated. LMC P3 is the most luminous gamma-ray binary known so far.
KW  - gamma rays: stars
KW  - binaries: general
KW  - stars: massive
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201732426
SN  - 1432-0746
VL  - 610
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Abdoul-Carime, Hassan
A1  - Bald, Ilko
A1  - Illenberger, Eugen
A1  - Kopyra, Janina
T1  - Selective Synthesis of Ethylene and Acetylene from Dimethyl Sulfide Cold Films Controlled by Slow Electrons
JF  - The journal of physical chemistry : C, Nanomaterials and interfaces
N2  - One of the major challenges in chemical synthesis is to trigger and control a specific reaction route leading to a specific final product, while side products are avoided. Methodologies based on resonant processes at the molecular level, for example, photochemistry, offer the possibility of inducing selective reactions. Electrons at energies below the molecular ionization potential (<10 eV) are known to dissociate molecules via resonant processes with higher cross sections and specificity than photons. Here we show that even subexcitation electrons with energies as low as 1 eV produce ethylene and acetylene from dimethyl sulfide in competing reactions. However, the production of ethylene can specifically be targeted by controlling the energy of electrons (similar to 3 to 4 eV). Finally, pure ethylene is selectively desorbed by heating the substrate from 90 to 105 K. Beyond the synthesis of these versatile hydrocarbons for various industrial applications from a biogenic sulfur compound, our findings demonstrate the feasibility of electron induced selective chemistry applicable on the nanoscale.
Y1  - 2018
U6  - https://doi.org/10.1021/acs.jpcc.8b07377
SN  - 1932-7447
VL  - 122
IS  - 42
SP  - 24137
EP  - 24142
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archambault, S.
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Byrum, K.
A1  - Cerruti, M.
A1  - Chen, X.
A1  - Ciupik, L.
A1  - Cui, W.
A1  - Dickinson, H. J.
A1  - Eisch, J. D.
A1  - Errando, M.
A1  - Falcone, A.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fleischhack, H.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Gillanders, G. H.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Hutten, M.
A1  - Hakansson, N.
A1  - Hanna, D.
A1  - Holder, J.
A1  - Humensky, T. B.
A1  - Johnson, C. A.
A1  - Kaaret, P.
A1  - Kar, P.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krause, M.
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Maier, G.
A1  - McArthur, S.
A1  - McCann, A.
A1  - Meagher, K.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nguyen, T.
A1  - Nieto, D.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Pelassa, V.
A1  - Pohl, Martin
A1  - Popkow, A.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Staszak, D.
A1  - Telezhinsky, Igor O.
A1  - Tucci, J. V.
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weiner, O. M.
A1  - Weinstein, A.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Fegan, S.
A1  - Giebels, B.
A1  - Horan, D.
A1  - Berdyugin, A.
A1  - Kuan, J.
A1  - Lindfors, E.
A1  - Nilsson, K.
A1  - Oksanen, A.
A1  - Prokoph, H.
A1  - Reinthal, R.
A1  - Takalo, L.
A1  - Zefi, F.
T1  - A Luminous and Isolated Gamma-Ray Flare from the Blazar B2 1215+30
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - B2 1215+30 is a BL-Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes and subsequently confirmed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory with data collected between 2009 and 2012. In 2014 February 08, VERITAS detected a large-amplitude flare from B2. 1215+30 during routine monitoring observations of the blazar 1ES. 1218+304, located in the same field of view. The TeV flux reached 2.4 times the Crab Nebula flux with a variability timescale of <3.6 hr. Multiwavelength observations with Fermi-LAT, Swift, and the Tuorla Observatory revealed a correlated high GeV flux state and no significant optical counterpart to the flare, with a spectral energy distribution where the gamma-ray luminosity exceeds the synchrotron luminosity. When interpreted in the framework of a onezone leptonic model, the observed emission implies a high degree of beaming, with Doppler factor delta > 10, and an electron population with spectral index p < 2.3.
KW  - BL Lacertae objects: individual (B2 1215+30, VER J1217+301)
KW  - galaxies: active
KW  - galaxies: jets
KW  - galaxies: nuclei
KW  - gamma rays: galaxies
Y1  - 2017
U6  - https://doi.org/10.3847/1538-4357/836/2/205
SN  - 0004-637X
SN  - 1538-4357
VL  - 836
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archer, A.
A1  - Aune, Taylor
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Bugaev, V.
A1  - Cui, Wei
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Fleischhack, H.
A1  - Flinders, A.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Gotthelf, Eric V.
A1  - Grube, J.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Huang, K.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Huetten, M.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, Maria
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - Maier, Gernot
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, Adam Nepomuk
A1  - Pandel, Dirk
A1  - Park, Nahee
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Popkow, Alexis
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rousselle, J.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Tyler, J.
A1  - Vassiliev, V. V.
A1  - Wakely, S. P.
A1  - Ward, J. E.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, David A.
A1  - Zitzer, B.
T1  - A Very High Energy gamma-Ray Survey toward the Cygnus Region of the Galaxy
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We present results from deep observations toward the Cygnus region using 300 hr of very high energy (VHE)gamma-ray data taken with the VERITAS Cerenkov telescope array and over 7 yr of high-energy.-ray data taken with the Fermi satellite at an energy above 1 GeV. As the brightest region of diffuse gamma-ray emission in the northern sky, the Cygnus region provides a promising area to probe the origins of cosmic rays. We report the identification of a potential Fermi-LAT counterpart to VER J2031+415 (TeV J2032+4130) and resolve the extended VHE source VER J2019+368 into two source candidates (VER J2018+367* and VER J2020+368*) and characterize their energy spectra. The Fermi-LAT morphology of 3FGL J2021.0+4031e (the Gamma Cygni supernova remnant) was examined, and a region of enhanced emission coincident with VER J2019+407 was identified and jointly fit with the VERITAS data. By modeling 3FGL J2015.6+3709 as two sources, one located at the location of the pulsar wind nebula CTB 87 and one at the quasar QSO J2015+371, a continuous spectrum from 1 GeV to 10 TeV was extracted for VER J2016+371 (CTB 87). An additional 71 locations coincident with Fermi-LAT sources and other potential objects of interest were tested for VHE gamma-ray emission, with no emission detected and upper limits on the differential flux placed at an average of 2.3% of the Crab Nebula flux. We interpret these observations in a multiwavelength context and present the most detailed gamma-ray view of the region to date.
KW  - acceleration of particles
KW  - cosmic rays
KW  - gamma rays: general
KW  - ISM: supernova remnants
Y1  - 2018
U6  - https://doi.org/10.3847/1538-4357/aac4a2
SN  - 0004-637X
SN  - 1538-4357
VL  - 861
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brill, A.
A1  - Brose, Robert
A1  - Buckley, J. H.
A1  - Christiansen, Jessie L.
A1  - Chromey, A. J.
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Gillanders, Gerard H.
A1  - Gueta, O.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, Maria
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, Marcos
A1  - Scott, S. S.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Williamson, T. J.
A1  - Zitzer, B.
A1  - Kaur, A.
T1  - VERITAS Observations of the BL Lac Object TXS 0506+056
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
N2  - On 2017 September 22, the IceCube Neutrino Observatory reported the detection of the high-energy neutrino event IC 170922A, of potential astrophysical origin. It was soon determined that the neutrino direction was consistent with the location of the gamma-ray blazar TXS 0506+056. (3FGL J0509.4+ 0541), which was in an elevated gamma-ray emission state as measured by the Fermi satellite. Very Energetic Radiation Imaging Telescope Array System (VERITAS) observations of the neutrino/blazar region started on 2017 September 23 in response to the neutrino alert and continued through 2018 February 6. While no significant very-high-energy (VHE; E > 100 GeV) emission was observed from the blazar by VERITAS in the two-week period immediately following the IceCube alert, TXS 0506+ 056 was detected by VERITAS with a significance of 5.8 standard deviations (sigma) in the full 35 hr data set. The average photon flux of the source during this period was (8.9 +/- 1.6). x. 10(-12) cm(-2) s(-1), or 1.6% of the Crab Nebula flux, above an energy threshold of 110 GeV, with a soft spectral index of 4.8. +/-. 1.3.
KW  - astroparticle physics
KW  - BL Lacertae objects: individual (TXS 0506+056, VER J0509+057)
KW  - gamma rays: galaxies
KW  - quasars: general
KW  - neutrinos
Y1  - 2018
U6  - https://doi.org/10.3847/2041-8213/aad053
SN  - 2041-8205
SN  - 2041-8213
VL  - 861
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Chromey, A. J.
A1  - Connolly, M. P.
A1  - Cui, Wei
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Huetten, M.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, M.
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, Adam Nepomuk
A1  - Park, Nahee
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, Marcos
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Sushch, I.
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Williamson, T. J.
A1  - Zitzer, B.
A1  - Abdollahi, S.
A1  - Ajello, Marco
A1  - Baldini, Luca
A1  - Barbiellini, G.
A1  - Bastieri, Denis
A1  - Bellazzini, Ronaldo
A1  - Berenji, B.
A1  - Bissaldi, Elisabetta
A1  - Blandford, R. D.
A1  - Bonino, R.
A1  - Bottacini, E.
A1  - Brandt, Terri J.
A1  - Bruel, P.
A1  - Buehler, R.
A1  - Cameron, R. A.
A1  - Caputo, R.
A1  - Caraveo, P. A.
A1  - Castro, D.
A1  - Cavazzuti, E.
A1  - Charles, Eric
A1  - Chiaro, G.
A1  - Ciprini, S.
A1  - Cohen-Tanugi, Johann
A1  - Costantin, D.
A1  - Cutini, S.
A1  - de Palma, F.
A1  - Di Lalla, N.
A1  - Di Mauro, M.
A1  - Di Venere, L.
A1  - Dominguez, A.
A1  - Favuzzi, C.
A1  - Fegan, S. J.
A1  - Franckowiak, Anna
A1  - Fukazawa, Yasushi
A1  - Funk, Stefan
A1  - Fusco, Piergiorgio
A1  - Gargano, Fabio
A1  - Gasparrini, Dario
A1  - Giglietto, Nicola
A1  - Giordano, F.
A1  - Giroletti, Marcello
A1  - Green, D.
A1  - Grenier, I. A.
A1  - Guillemot, L.
A1  - Guiriec, Sylvain
A1  - Hays, Elizabeth
A1  - Hewitt, John W.
A1  - Horan, D.
A1  - Johannesson, G.
A1  - Kensei, S.
A1  - Kuss, M.
A1  - Larsson, Stefan
A1  - Latronico, L.
A1  - Lemoine-Goumard, Marianne
A1  - Li, J.
A1  - Longo, Francesco
A1  - Loparco, Francesco
A1  - Lovellette, M. N.
A1  - Lubrano, Pasquale
A1  - Magill, Jeffrey D.
A1  - Maldera, Simone
A1  - Mazziotta, Mario Nicola
A1  - McEnery, J. E.
A1  - Michelson, P. F.
A1  - Mitthumsiri, W.
A1  - Mizuno, Tsunefumi
A1  - Monzani, Maria Elena
A1  - Morselli, Aldo
A1  - Moskalenko, Igor V.
A1  - Negro, M.
A1  - Nuss, E.
A1  - Ojha, R.
A1  - Omodei, Nicola
A1  - Orienti, M.
A1  - Orlando, E.
A1  - Palatiello, M.
A1  - Paliya, Vaidehi S.
A1  - Paneque, D.
A1  - Perkins, Jeremy S.
A1  - Persic, M.
A1  - Pesce-Rollins, Melissa
A1  - Petrosian, Vahe'
A1  - Piron, F.
A1  - Porter, Troy A.
A1  - Principe, G.
A1  - Raino, S.
A1  - Rando, Riccardo
A1  - Rani, B.
A1  - Razzano, Massimilano
A1  - Razzaque, Soebur
A1  - Reimer, A.
A1  - Reimer, Olaf
A1  - Reposeur, T.
A1  - Sgro, C.
A1  - Siskind, E. J.
A1  - Spandre, Gloria
A1  - Spinelli, P.
A1  - Suson, D. J.
A1  - Tajima, Hiroyasu
A1  - Thayer, J. B.
A1  - Thompson, David J.
A1  - Torres, Diego F.
A1  - Tosti, Gino
A1  - Troja, Eleonora
A1  - Valverde, J.
A1  - Vianello, Giacomo
A1  - Vogel, M.
A1  - Wood, K.
A1  - Yassine, M.
A1  - Alfaro, R.
A1  - Alvarez, C.
A1  - Alvarez, J. D.
A1  - Arceo, R.
A1  - Arteaga-Velazquez, J. C.
A1  - Rojas, D. Avila
A1  - Ayala Solares, H. A.
A1  - Becerril, A.
A1  - Belmont-Moreno, E.
A1  - BenZvi, S. Y.
A1  - Bernal, A.
A1  - Braun, J.
A1  - Brisbois, C.
A1  - Caballero-Mora, K. S.
A1  - Capistran, T.
A1  - Carraminana, A.
A1  - Casanova, Sabrina
A1  - Castillo, M.
A1  - Cotti, U.
A1  - Cotzomi, J.
A1  - Coutino de Leon, S.
A1  - De Leon, C.
A1  - De la Fuente, E.
A1  - Dichiara, S.
A1  - Dingus, B. L.
A1  - DuVernois, M. A.
A1  - Diaz-Velez, J. C.
A1  - Engel, K.
A1  - Enriquez-Rivera, O.
A1  - Fiorino, D. W.
A1  - Fleischhack, H.
A1  - Fraija, N.
A1  - Garcia-Gonzalez, J. A.
A1  - Garfias, F.
A1  - Gonzalez Munoz, A.
A1  - Gonzalez, M. M.
A1  - Goodman, J. A.
A1  - Hampel-Arias, Z.
A1  - Harding, J. P.
A1  - Hernandez, S.
A1  - Hernandez-Almada, A.
A1  - Hona, B.
A1  - Hueyotl-Zahuantitla, F.
A1  - Hui, C. M.
A1  - Huntemeyer, P.
A1  - Iriarte, A.
A1  - Jardin-Blicq, A.
A1  - Joshi, V.
A1  - Kaufmann, S.
A1  - Lara, A.
A1  - Lauer, R. J.
A1  - Lee, W. H.
A1  - Lennarz, D.
A1  - Leon Vargas, H.
A1  - Linnemann, J. T.
A1  - Longinotti, A. L.
A1  - Luis-Raya, G.
A1  - Luna-Garcia, R.
A1  - Lopez-Coto, R.
A1  - Malone, K.
A1  - Marinelli, S. S.
A1  - Martinez, O.
A1  - Martinez-Castellanos, I.
A1  - Martinez-Castro, J.
A1  - Martinez-Huerta, H.
A1  - Matthews, J. A.
A1  - Miranda-Romagnoli, P.
A1  - Moreno, E.
A1  - Mostafa, M.
A1  - Nayerhoda, A.
A1  - Nellen, L.
A1  - Newbold, M.
A1  - Nisa, M. U.
A1  - Noriega-Papaqui, R.
A1  - Pelayo, R.
A1  - Pretz, J.
A1  - Perez-Perez, E. G.
A1  - Ren, Z.
A1  - Rho, C. D.
A1  - Riviere, C.
A1  - Rosa-Gonzalez, D.
A1  - Rosenberg, M.
A1  - Ruiz-Velasco, E.
A1  - Salazar, H.
A1  - Greus, F. Salesa
A1  - Sandoval, A.
A1  - Schneider, M.
A1  - Arroyo, M. Seglar
A1  - Sinnis, G.
A1  - Smith, A. J.
A1  - Springer, R. W.
A1  - Surajbali, P.
A1  - Taboada, Ignacio
A1  - Tibolla, O.
A1  - Tollefson, K.
A1  - Torres, I.
A1  - Ukwatta, Tilan N.
A1  - Villasenor, L.
A1  - Weisgarber, T.
A1  - Westerhoff, Stefan
A1  - Wisher, I. G.
A1  - Wood, J.
A1  - Yapici, Tolga
A1  - Yodh, G.
A1  - Zepeda, A.
A1  - Zhou, H.
T1  - VERITAS and Fermi-LAT Observations of TeV Gamma-Ray Sources Discovered by HAWC in the 2HWC Catalog
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - The High Altitude Water Cherenkov (HAWC) collaboration recently published their 2HWC catalog, listing 39 very high energy (VHE; >100 GeV) gamma-ray sources based on 507 days of observation. Among these, 19 sources are not associated with previously known teraelectronvolt (TeV) gamma-ray sources. We have studied 14 of these sources without known counterparts with VERITAS and Fermi-LAT. VERITAS detected weak gamma-ray emission in the 1 TeV-30 TeV band in the region of DA 495, a pulsar wind nebula coinciding with 2HWC J1953+294, confirming the discovery of the source by HAWC. We did not find any counterpart for the selected 14 new HAWC sources from our analysis of Fermi-LAT data for energies higher than 10 GeV. During the search, we detected gigaelectronvolt (GeV) gamma-ray emission coincident with a known TeV pulsar wind nebula, SNR G54.1+0.3 (VER J1930+188), and a 2HWC source, 2HWC J1930+188. The fluxes for isolated, steady sources in the 2HWC catalog are generally in good agreement with those measured by imaging atmospheric Cherenkov telescopes. However, the VERITAS fluxes for SNR G54.1+0.3, DA 495, and TeV J2032+4130 are lower than those measured by HAWC, and several new HAWC sources are not detected by VERITAS. This is likely due to a change in spectral shape, source extension, or the influence of diffuse emission in the source region.
KW  - gamma rays: general
Y1  - 2018
U6  - https://doi.org/10.3847/1538-4357/aade4e
SN  - 0004-637X
SN  - 1538-4357
VL  - 866
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Bugaev, V.
A1  - Connolly, M. P.
A1  - Cui, Wei
A1  - Errando, Manel
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Flinders, A.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Gillanders, Gerard H.
A1  - Huetten, M.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, Maria
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - Maier, Gernot
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Park, N.
A1  - Perkins, Jeremy S.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Popkow, Alexis
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weiner, O. M.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, David A.
A1  - Zitzer, B.
A1  - Vurm, Indrek
A1  - Beloborodov, Andrei
T1  - A Strong Limit on the Very-high-energy Emission from GRB 150323A
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - On 2015 March 23, the Very Energetic Radiation Imaging Telescope Array System (VERITAS) responded to a Swift-Burst Alert Telescope (BAT) detection of a gamma-ray burst, with observations beginning 270 s after the onset of BAT emission, and only 135 s after the main BAT emission peak. No statistically significant signal is detected above 140 GeV. The VERITAS upper limit on the fluence in a 40-minute integration corresponds to about 1% of the prompt fluence. Our limit is particularly significant because the very-high-energy (VHE) observation started only similar to 2 minutes after the prompt emission peaked, and Fermi-Large Area Telescope observations of numerous other bursts have revealed that the high-energy emission is typically delayed relative to the prompt radiation and lasts significantly longer. Also, the proximity of GRB 150323A (z = 0.593) limits the attenuation by the extragalactic background light to similar to 50% at 100-200 GeV. We conclude that GRB 150323A had an intrinsically very weak high-energy afterglow, or that the GeV spectrum had a turnover below similar to 100 GeV. If the GRB exploded into the stellar wind of a massive progenitor, the VHE non-detection constrains the wind density parameter to be A greater than or similar to 3 x 10(11) g . cm(-1), consistent with a standard Wolf-Rayet progenitor. Alternatively, the VHE emission from the blast wave would be weak in a very tenuous medium such as the interstellar medium, which therefore cannot be ruled out as the environment of GRB 150323A.
KW  - gamma rays: general
KW  - gamma-ray burst: general
KW  - gamma-ray burst: individual (GRB 150323A)
Y1  - 2018
U6  - https://doi.org/10.3847/1538-4357/aab371
SN  - 0004-637X
SN  - 1538-4357
VL  - 857
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brantseg, T.
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Connolly, M. P.
A1  - Cui, Wei
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Gillanders, Gerard H.
A1  - Gunawardhana, Isuru
A1  - Huetten, M.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kertzman, M.
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, Adam Nepomuk
A1  - Park, N.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Williams, D. A.
A1  - Zitzer, B.
A1  - Jorstad, Svetlana G.
A1  - Marscher, Alan P.
A1  - Lister, Matthew L.
A1  - Kovalev, Yuri Y.
A1  - Pushkarev, A. B.
A1  - Savolainen, Tuomas
A1  - Agudo, I.
A1  - Molina, S. N.
A1  - Gomez, J. L.
A1  - Larionov, Valeri M.
A1  - Borman, G. A.
A1  - Mokrushina, A. A.
A1  - Tornikoski, Merja
A1  - Lahteenmaki, A.
A1  - Chamani, W.
A1  - Enestam, S.
A1  - Kiehlmann, S.
A1  - Hovatta, Talvikki
A1  - Smith, P. S.
A1  - Pontrelli, P.
T1  - Multiwavelength Observations of the Blazar BL Lacertae
BT  - a new Fast TeV Gamma-Ray Flare
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - Combined with measurements made by very-long-baseline interferometry, the observations of fast TeV gamma-ray flares probe the structure and emission mechanism of blazar jets. However, only a handful of such flares have been detected to date, and only within the last few years have these flares been observed from lower-frequency-peaked BL. Lac objects and flat-spectrum radio quasars. We report on a fast TeV gamma-ray flare from the blazar BL. Lacertae observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS). with a rise time of similar to 2.3 hr and a decay time of similar to 36 min. The peak flux above 200 GeV is (4.2 +/- 0.6) x 10(-6) photon m(-2) s(-1) measured with a 4-minute-binned light curve, corresponding to similar to 180% of the flux that is observed from the Crab Nebula above the same energy threshold. Variability contemporaneous with the TeV gamma-ray flare was observed in GeV gamma-ray, X-ray, and optical flux, as well as in optical and radio polarization. Additionally, a possible moving emission feature with superluminal apparent velocity was identified in Very Long Baseline Array observations at 43 GHz, potentially passing the radio core of the jet around the time of the gamma-ray flare. We discuss the constraints on the size, Lorentz factor, and location of the emitting region of the flare, and the interpretations with several theoretical models that invoke relativistic plasma passing stationary shocks.
KW  - BL Lacertae objects: individual (BL Lacertae = VER J2202+422)
KW  - galaxies: active
Y1  - 2018
U6  - https://doi.org/10.3847/1538-4357/aab35c
SN  - 0004-637X
SN  - 1538-4357
VL  - 856
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abiuso, Paolo
A1  - Holubec, Viktor
A1  - Anders, Janet
A1  - Ye, Zhuolin
A1  - Cerisola, Federico
A1  - Perarnau-Llobet, Marti
T1  - Thermodynamics and optimal protocols of multidimensional quadratic Brownian systems
JF  - Journal of physics communications
N2  - We characterize finite-time thermodynamic processes of multidimensional quadratic overdamped systems. 
Analytic expressions are provided for heat, work, and dissipation for any evolution of the system covariance matrix. 
The Bures-Wasserstein metric between covariance matrices naturally emerges as the local quantifier of dissipation. 
General principles of how to apply these geometric tools to identify optimal protocols are discussed. 
Focusing on the relevant slow-driving limit, we show how these results can be used to analyze cases in which the experimental control over the system is partial.
KW  - stochastic thermodynamics
KW  - thermodynamic control
KW  - thermodynamic length
KW  - overdamped brownian systems
Y1  - 2022
U6  - https://doi.org/10.1088/2399-6528/ac72f8
SN  - 2399-6528
VL  - 6
IS  - 6
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abramowski, A.
A1  - Aharonian, Felix A.
A1  - Benkhali, F. Ait
A1  - Akhperjanian, A. G.
A1  - Anguener, E. O.
A1  - Backes, M.
A1  - Balzer, A.
A1  - Becherini, Y.
A1  - Tjus, J. Becker
A1  - Berge, D.
A1  - Bernhard, S.
A1  - Bernloehr, K.
A1  - Birsin, E.
A1  - Blackwell, R.
A1  - Boettcher, M.
A1  - Boisson, C.
A1  - Bolmont, J.
A1  - Bordas, Pol
A1  - Bregeon, J.
A1  - Brun, F.
A1  - Brun, P.
A1  - Bryan, M.
A1  - Bulik, T.
A1  - Carr, J.
A1  - Casanova, Sabrina
A1  - Chakraborty, N.
A1  - Chalme-Calvet, R.
A1  - Chaves, R. C. G.
A1  - Chen, A.
A1  - Chevalier, J.
A1  - Chretien, M.
A1  - Colafrancesco, S.
A1  - Cologna, G.
A1  - Condon, B.
A1  - Conrad, J.
A1  - Couturier, C.
A1  - Cui, Y.
A1  - Davids, I. D.
A1  - Degrange, B.
A1  - Deil, C.
A1  - deWilt, P.
A1  - Djannati-Atai, A.
A1  - Domainko, W.
A1  - Donath, A.
A1  - Dubus, G.
A1  - Dutson, K.
A1  - Dyks, J.
A1  - Dyrda, M.
A1  - Edwards, T.
A1  - Egberts, Kathrin
A1  - Eger, P.
A1  - Ernenwein, J. -P.
A1  - Espigat, P.
A1  - Farnier, C.
A1  - Fegan, S.
A1  - Feinstein, F.
A1  - Fernandes, M. V.
A1  - Fernandez, D.
A1  - Fiasson, A.
A1  - Fontaine, G.
A1  - Foerster, A.
A1  - Fuessling, M.
A1  - Gabici, S.
A1  - Gajdus, M.
A1  - Gallant, Y. A.
A1  - Garrigoux, T.
A1  - Giavitto, G.
A1  - Giebels, B.
A1  - Glicenstein, J. F.
A1  - Gottschall, D.
A1  - Goyal, A.
A1  - Grondin, M. -H.
A1  - Grudzinska, M.
A1  - Hadasch, D.
A1  - Haeffner, S.
A1  - Hahn, J.
A1  - Hawkes, J.
A1  - Heinzelmann, G.
A1  - Henri, G.
A1  - Hermann, G.
A1  - Hervet, O.
A1  - Hillert, A.
A1  - Hinton, J. A.
A1  - Hofmann, W.
A1  - Hofverberg, P.
A1  - Hoischen, Clemens
A1  - Holler, M.
A1  - Horns, D.
A1  - Ivascenko, A.
A1  - Jacholkowska, A.
A1  - Jamrozy, M.
A1  - Janiak, M.
A1  - Jankowsky, F.
A1  - Jung-Richardt, I.
A1  - Kastendieck, M. A.
A1  - Katarzynski, K.
A1  - Katz, U.
A1  - Kerszberg, D.
A1  - Khelifi, B.
A1  - Kieffer, M.
A1  - Klepser, S.
A1  - Klochkov, D.
A1  - Kluzniak, W.
A1  - Kolitzus, D.
A1  - Komin, Nu.
A1  - Kosack, K.
A1  - Krakau, S.
A1  - Krayzel, F.
A1  - Krueger, P. P.
A1  - Laffon, H.
A1  - Lamanna, G.
A1  - Lau, J.
A1  - Lefaucheur, J.
A1  - Lefranc, V.
A1  - Lemiere, A.
A1  - Lemoine-Goumard, M.
A1  - Lenain, J. -P.
A1  - Lohse, T.
A1  - Lopatin, A.
A1  - Lorentz, M.
A1  - Lu, C. -C.
A1  - Lui, R.
A1  - Marandon, V.
A1  - Marcowith, Alexandre
A1  - Mariaud, C.
A1  - Marx, R.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Mayer, M.
A1  - Meintjes, P. J.
A1  - Menzler, U.
A1  - Meyer, M.
A1  - Mitchell, A. M. W.
A1  - Moderski, R.
A1  - Mohamed, M.
A1  - Mora, K.
A1  - Moulin, Emmanuel
A1  - Murach, T.
A1  - de Naurois, M.
A1  - Niemiec, J.
A1  - Oakes, L.
A1  - Odaka, H.
A1  - Oettl, S.
A1  - Ohm, S.
A1  - Opitz, B.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Panter, M.
A1  - Parsons, R. D.
A1  - Arribas, M. Paz
A1  - Pekeur, N. W.
A1  - Pelletier, G.
A1  - Petrucci, P. -O.
A1  - Peyaud, B.
A1  - Pita, S.
A1  - Poon, H.
A1  - Prokhorov, D.
A1  - Prokoph, H.
A1  - Puehlhofer, G.
A1  - Punch, M.
A1  - Quirrenbach, A.
A1  - Raab, S.
A1  - Reichardt, I.
A1  - Reimer, A.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - de los Reyes, R.
A1  - Rieger, F.
A1  - Romoli, C.
A1  - Rosier-Lees, S.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Rulten, C. B.
A1  - Sahakian, V.
A1  - Salek, D.
A1  - Sanchez, D. A.
A1  - Santangelo, A.
A1  - Sasaki, M.
A1  - Schlickeiser, R.
A1  - Schuessler, F.
A1  - Schulz, A.
A1  - Schwanke, U.
A1  - Schwemmer, S.
A1  - Seyffert, A. S.
A1  - Simoni, R.
A1  - Sol, H.
A1  - Spanier, F.
A1  - Spengler, G.
A1  - Spies, F.
A1  - Stawarz, L.
A1  - Steenkamp, R.
A1  - Stegmann, Christian
A1  - Stinzing, F.
A1  - Stycz, K.
A1  - Sushch, I.
A1  - Tavernet, J. -P.
A1  - Tavernier, T.
A1  - Taylor, A. M.
A1  - Terrier, R.
A1  - Tluczykont, M.
A1  - Trichard, C.
A1  - Tuffs, R.
A1  - Valerius, K.
A1  - van der Walt, J.
A1  - van Eldik, C.
A1  - van Soelen, B.
A1  - Vasileiadis, G.
A1  - Veh, J.
A1  - Venter, C.
A1  - Viana, A.
A1  - Vincent, P.
A1  - Vink, J.
A1  - Voisin, F.
A1  - Voelk, H. J.
A1  - Vuillaume, T.
A1  - Wagner, S. J.
A1  - Wagner, P.
A1  - Wagner, R. M.
A1  - Weidinger, M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Willmann, P.
A1  - Woernlein, A.
A1  - Wouters, D.
A1  - Yang, R.
A1  - Zabalza, V.
A1  - Zaborov, D.
A1  - Zacharias, M.
A1  - Zdziarski, A. A.
A1  - Zech, Alraune
A1  - Zefi, F.
A1  - Zywucka, N.
T1  - Detailed spectral and morphological analysis of the shell type supernova remnant RCW 86
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Aims. We aim for an understanding of the morphological and spectral properties of the supernova remnant RCW 86 and for insights into the production mechanism leading to the RCW 86 very high-energy gamma-ray emission. Methods. We analyzed High Energy Spectroscopic System (H.E.S.S.) data that had increased sensitivity compared to the observations presented in the RCW 86 H.E.S.S. discovery publication. Studies of the morphological correlation between the 0.5-1 keV X-ray band, the 2-5 keV X-ray band, radio, and gamma-ray emissions have been performed as well as broadband modeling of the spectral energy distribution with two different emission models. Results. We present the first conclusive evidence that the TeV gamma-ray emission region is shell-like based on our morphological studies. The comparison with 2-5 keV X-ray data reveals a correlation with the 0.4-50 TeV gamma-ray emission. The spectrum of RCW 86 is best described by a power law with an exponential cutoff at E-cut = (3.5 +/- 1.2(stat)) TeV and a spectral index of Gamma approximate to 1.6 +/- 0.2. A static leptonic one-zone model adequately describes the measured spectral energy distribution of RCW 86, with the resultant total kinetic energy of the electrons above 1 GeV being equivalent to similar to 0.1% of the initial kinetic energy of a Type Ia supernova explosion (10(51) erg). When using a hadronic model, a magnetic field of B approximate to 100 mu G is needed to represent the measured data. Although this is comparable to formerly published estimates, a standard E-2 spectrum for the proton distribution cannot describe the gamma-ray data. Instead, a spectral index of Gamma(p) approximate to 1.7 would be required, which implies that similar to 7 x 10(49)/n(cm-3) erg has been transferred into high-energy protons with the effective density n(cm-3) = n/1 cm(-3). This is about 10% of the kinetic energy of a typical Type Ia supernova under the assumption of a density of 1 cm(-3).
KW  - astroparticle physics
KW  - gamma rays: general
KW  - ISM: supernova remnants
KW  - cosmic rays
Y1  - 2018
U6  - https://doi.org/10.1051/0004-6361/201526545
SN  - 1432-0746
VL  - 612
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Acero, F.
A1  - Aloisio, R.
A1  - Amans, J.
A1  - Amato, Elena
A1  - Antonelli, L. A.
A1  - Aramo, C.
A1  - Armstrong, T.
A1  - Arqueros, F.
A1  - Asano, Katsuaki
A1  - Ashley, M.
A1  - Backes, M.
A1  - Balazs, C.
A1  - Balzer, A.
A1  - Bamba, Aya
A1  - Barkov, Maxim
A1  - Barrio, J. A.
A1  - Benbow, Wystan
A1  - Bernloehr, K.
A1  - Beshley, V.
A1  - Bigongiari, C.
A1  - Biland, A.
A1  - Bilinsky, A.
A1  - Bissaldi, Elisabetta
A1  - Biteau, J.
A1  - Blanch, O.
A1  - Blasi, P.
A1  - Blazek, J.
A1  - Boisson, C.
A1  - Bonanno, G.
A1  - Bonardi, A.
A1  - Bonavolonta, C.
A1  - Bonnoli, G.
A1  - Braiding, C.
A1  - Brau-Nogue, S.
A1  - Bregeon, J.
A1  - Brown, A. M.
A1  - Bugaev, V.
A1  - Bulgarelli, A.
A1  - Bulik, T.
A1  - Burton, Michael
A1  - Burtovoi, A.
A1  - Busetto, G.
A1  - Bottcher, M.
A1  - Cameron, R.
A1  - Capalbi, M.
A1  - Caproni, Anderson
A1  - Caraveo, P.
A1  - Carosi, R.
A1  - Cascone, E.
A1  - Cerruti, M.
A1  - Chaty, Sylvain
A1  - Chen, A.
A1  - Chen, X.
A1  - Chernyakova, M.
A1  - Chikawa, M.
A1  - Chudoba, J.
A1  - Cohen-Tanugi, J.
A1  - Colafrancesco, S.
A1  - Conforti, V.
A1  - Contreras, J. L.
A1  - Costa, A.
A1  - Cotter, G.
A1  - Covino, Stefano
A1  - Covone, G.
A1  - Cumani, P.
A1  - Cusumano, G.
A1  - Daniel, M.
A1  - Dazzi, F.
A1  - De Angelis, A.
A1  - De Cesare, G.
A1  - De Franco, A.
A1  - De Frondat, F.
A1  - Dal Pino, E. M. de Gouveia
A1  - De Lisio, C.
A1  - Lopez, R. de los Reyes
A1  - De Lotto, B.
A1  - de Naurois, M.
A1  - De Palma, F.
A1  - Del Santo, M.
A1  - Delgado, C.
A1  - della Volpe, D.
A1  - Di Girolamo, T.
A1  - Di Giulio, C.
A1  - Di Pierro, F.
A1  - Di Venere, L.
A1  - Doro, M.
A1  - Dournaux, J.
A1  - Dumas, D.
A1  - Dwarkadas, Vikram V.
A1  - Diaz, C.
A1  - Ebr, J.
A1  - Egberts, Kathrin
A1  - Einecke, S.
A1  - Elsaesser, D.
A1  - Eschbach, S.
A1  - Falceta-Goncalves, D.
A1  - Fasola, G.
A1  - Fedorova, E.
A1  - Fernandez-Barral, A.
A1  - Ferrand, Gilles
A1  - Fesquet, M.
A1  - Fiandrini, E.
A1  - Fiasson, A.
A1  - Filipovic, Miroslav D.
A1  - Fioretti, V.
A1  - Font, L.
A1  - Fontaine, Gilles
A1  - Franco, F. J.
A1  - Freixas Coromina, L.
A1  - Fujita, Yutaka
A1  - Fukui, Y.
A1  - Funk, S.
A1  - Forster, A.
A1  - Gadola, A.
A1  - Lopez, R. Garcia
A1  - Garczarczyk, M.
A1  - Giglietto, N.
A1  - Giordano, F.
A1  - Giuliani, A.
A1  - Glicenstein, J.
A1  - Gnatyk, R.
A1  - Goldoni, P.
A1  - Grabarczyk, T.
A1  - Graciani, R.
A1  - Graham, J.
A1  - Grandi, P.
A1  - Granot, Jonathan
A1  - Green, A. J.
A1  - Griffiths, S.
A1  - Gunji, S.
A1  - Hakobyan, H.
A1  - Hara, S.
A1  - Hassan, T.
A1  - Hayashida, M.
A1  - Heller, M.
A1  - Helo, J. C.
A1  - Hinton, J.
A1  - Hnatyk, B.
A1  - Huet, J.
A1  - Huetten, M.
A1  - Humensky, T. B.
A1  - Hussein, M.
A1  - Horandel, J.
A1  - Ikeno, Y.
A1  - Inada, T.
A1  - Inome, Y.
A1  - Inoue, S.
A1  - Inoue, T.
A1  - Inoue, Y.
A1  - Ioka, K.
A1  - Iori, Maurizio
A1  - Jacquemier, J.
A1  - Janecek, P.
A1  - Jankowsky, D.
A1  - Jung, I.
A1  - Kaaret, P.
A1  - Katagiri, H.
A1  - Kimeswenger, S.
A1  - Kimura, Shigeo S.
A1  - Knodlseder, J.
A1  - Koch, B.
A1  - Kocot, J.
A1  - Kohri, K.
A1  - Komin, N.
A1  - Konno, Y.
A1  - Kosack, K.
A1  - Koyama, S.
A1  - Kraus, Michaela
A1  - Kubo, Hidetoshi
A1  - Mezek, G. Kukec
A1  - Kushida, J.
A1  - La Palombara, N.
A1  - Lalik, K.
A1  - Lamanna, G.
A1  - Landt, H.
A1  - Lapington, J.
A1  - Laporte, P.
A1  - Lee, S.
A1  - Lees, J.
A1  - Lefaucheur, J.
A1  - Lenain, J. -P.
A1  - Leto, Giuseppe
A1  - Lindfors, E.
A1  - Lohse, T.
A1  - Lombardi, S.
A1  - Longo, F.
A1  - Lopez, M.
A1  - Lucarelli, F.
A1  - Luque-Escamilla, Pedro Luis
A1  - Lopez-Coto, R.
A1  - Maccarone, M. C.
A1  - Maier, G.
A1  - Malaguti, G.
A1  - Mandat, D.
A1  - Maneva, G.
A1  - Mangano, S.
A1  - Marcowith, Alexandre
A1  - Marti, J.
A1  - Martinez, M.
A1  - Martinez, G.
A1  - Masuda, S.
A1  - Maurin, G.
A1  - Maxted, N.
A1  - Melioli, Claudio
A1  - Mineo, T.
A1  - Mirabal, N.
A1  - Mizuno, T.
A1  - Moderski, R.
A1  - Mohammed, M.
A1  - Montaruli, T.
A1  - Moralejo, A.
A1  - Mori, K.
A1  - Morlino, G.
A1  - Morselli, A.
A1  - Moulin, Emmanuel
A1  - Mukherjee, R.
A1  - Mundell, C.
A1  - Muraishi, H.
A1  - Murase, Kohta
A1  - Nagataki, Shigehiro
A1  - Nagayoshi, T.
A1  - Naito, T.
A1  - Nakajima, D.
A1  - Nakamori, T.
A1  - Nemmen, R.
A1  - Niemiec, Jacek
A1  - Nieto, D.
A1  - Nievas-Rosillo, M.
A1  - Nikolajuk, M.
A1  - Nishijima, K.
A1  - Noda, K.
A1  - Nogues, L.
A1  - Nosek, D.
A1  - Novosyadlyj, B.
A1  - Nozaki, S.
A1  - Ohira, Yutaka
A1  - Ohishi, M.
A1  - Ohm, S.
A1  - Okumura, A.
A1  - Ong, R. A.
A1  - Orito, R.
A1  - Orlati, A.
A1  - Ostrowski, M.
A1  - Oya, I.
A1  - Padovani, Marco
A1  - Palacio, J.
A1  - Palatka, M.
A1  - Paredes, Josep M.
A1  - Pavy, S.
A1  - Persic, M.
A1  - Petrucci, P.
A1  - Petruk, Oleh
A1  - Pisarski, A.
A1  - Pohl, Martin
A1  - Porcelli, A.
A1  - Prandini, E.
A1  - Prast, J.
A1  - Principe, G.
A1  - Prouza, M.
A1  - Pueschel, Elisa
A1  - Puelhofer, G.
A1  - Quirrenbach, A.
A1  - Rameez, M.
A1  - Reimer, O.
A1  - Renaud, M.
A1  - Ribo, M.
A1  - Rico, J.
A1  - Rizi, V.
A1  - Rodriguez, J.
A1  - Fernandez, G. Rodriguez
A1  - Rodriguez Vazquez, J. J.
A1  - Romano, Patrizia
A1  - Romeo, G.
A1  - Rosado, J.
A1  - Rousselle, J.
A1  - Rowell, G.
A1  - Rudak, B.
A1  - Sadeh, I.
A1  - Safi-Harb, S.
A1  - Saito, T.
A1  - Sakaki, N.
A1  - Sanchez, D.
A1  - Sangiorgi, P.
A1  - Sano, H.
A1  - Santander, M.
A1  - Sarkar, S.
A1  - Sawada, M.
A1  - Schioppa, E. J.
A1  - Schoorlemmer, H.
A1  - Schovanek, P.
A1  - Schussler, F.
A1  - Sergijenko, O.
A1  - Servillat, M.
A1  - Shalchi, A.
A1  - Shellard, R. C.
A1  - Siejkowski, H.
A1  - Sillanpaa, A.
A1  - Simone, D.
A1  - Sliusar, V.
A1  - Sol, H.
A1  - Stanic, S.
A1  - Starling, R.
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A1  - Stefanik, S.
A1  - Stephan, M.
A1  - Stolarczyk, T.
A1  - Szanecki, M.
A1  - Szepieniec, T.
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A1  - Takahashi, M.
A1  - Takeda, J.
A1  - Tanaka, M.
A1  - Tanaka, S.
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A1  - Telezhinsky, Igor O.
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A1  - Teshima, M.
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A1  - Townsley, C.
A1  - Travnicek, P.
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A1  - Trifoglio, M.
A1  - Tsujimoto, S.
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A1  - Vallania, P.
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A1  - van Driel, W.
A1  - van Eldik, C.
A1  - Vandenbroucke, Justin
A1  - Vassiliev, V.
A1  - Vecchi, M.
A1  - Vercellone, Stefano
A1  - Vergani, S.
A1  - Vigorito, C.
A1  - Vorobiov, S.
A1  - Vrastil, M.
A1  - Vazquez Acosta, M. L.
A1  - Wagner, S. J.
A1  - Wagner, R.
A1  - Wakely, S. P.
A1  - Walter, R.
A1  - Ward, J. E.
A1  - Watson, J. J.
A1  - Weinstein, A.
A1  - White, M.
A1  - White, R.
A1  - Wierzcholska, A.
A1  - Wilcox, P.
A1  - Williams, D. A.
A1  - Wischnewski, R.
A1  - Wojcik, P.
A1  - Yamamoto, T.
A1  - Yamamoto, H.
A1  - Yamazaki, Ryo
A1  - Yanagita, S.
A1  - Yang, L.
A1  - Yoshida, T.
A1  - Yoshida, M.
A1  - Yoshiike, S.
A1  - Yoshikoshi, T.
A1  - Zacharias, M.
A1  - Zampieri, L.
A1  - Zanin, R.
A1  - Zavrtanik, M.
A1  - Zavrtanik, D.
A1  - Zdziarski, A.
A1  - Zech, Alraune
A1  - Zechlin, Hannes
A1  - Zhdanov, V.
A1  - Ziegler, A.
A1  - Zorn, J.
T1  - Prospects for Cherenkov Telescope Array Observations of the Young Supernova Remnant RX J1713.7-3946
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We perform simulations for future Cherenkov Telescope Array (CTA) observations of RX J1713.7-3946, a young supernova remnant (SNR) and one of the brightest sources ever discovered in very high energy (VHE) gamma rays. Special attention is paid to exploring possible spatial (anti) correlations of gamma rays with emission at other wavelengths, in particular X-rays and CO/H I emission. We present a series of simulated images of RX J1713.7-3946 for CTA based on a set of observationally motivated models for the gamma-ray emission. In these models, VHE gamma rays produced by high-energy electrons are assumed to trace the nonthermal X-ray emission observed by XMM-Newton, whereas those originating from relativistic protons delineate the local gas distributions. The local atomic and molecular gas distributions are deduced by the NANTEN team from CO and H I observations. Our primary goal is to show how one can distinguish the emission mechanism(s) of the gamma rays (i.e., hadronic versus leptonic, or a mixture of the two) through information provided by their spatial distribution, spectra, and time variation. This work is the first attempt to quantitatively evaluate the capabilities of CTA to achieve various proposed scientific goals by observing this important cosmic particle accelerator.
KW  - cosmic rays
KW  - gamma rays: ISM
KW  - ISM: individual objects (RX J1713.7-3946, G347.3-0.5)
Y1  - 2017
U6  - https://doi.org/10.3847/1538-4357/aa6d67
SN  - 0004-637X
SN  - 1538-4357
VL  - 840
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Adolfs, Marjolijn
A1  - Hoque, Mohammed Mainul
A1  - Shprits, Yuri Y.
T1  - Storm-time relative total electron content modelling using machine learning techniques
JF  - Remote sensing
N2  - Accurately predicting total electron content (TEC) during geomagnetic storms is still a challenging task for ionospheric models. In this work, a neural-network (NN)-based model is proposed which predicts relative TEC with respect to the preceding 27-day median TEC, during storm time for the European region (with longitudes 30 degrees W-50 degrees E and latitudes 32.5 degrees N-70 degrees N). The 27-day median TEC (referred to as median TEC), latitude, longitude, universal time, storm time, solar radio flux index F10.7, global storm index SYM-H and geomagnetic activity index Hp30 are used as inputs and the output of the network is the relative TEC. The relative TEC can be converted to the actual TEC knowing the median TEC. The median TEC is calculated at each grid point over the European region considering data from the last 27 days before the storm using global ionosphere maps (GIMs) from international GNSS service (IGS) sources. A storm event is defined when the storm time disturbance index Dst drops below 50 nanotesla. The model was trained with storm-time relative TEC data from the time period of 1998 until 2019 (2015 is excluded) and contains 365 storms. Unseen storm data from 33 storm events during 2015 and 2020 were used to test the model. The UQRG GIMs were used because of their high temporal resolution (15 min) compared to other products from different analysis centers. The NN-based model predictions show the seasonal behavior of the storms including positive and negative storm phases during winter and summer, respectively, and show a mixture of both phases during equinoxes. The model's performance was also compared with the Neustrelitz TEC model (NTCM) and the NN-based quiet-time TEC model, both developed at the German Aerospace Agency (DLR). The storm model has a root mean squared error (RMSE) of 3.38 TEC units (TECU), which is an improvement by 1.87 TECU compared to the NTCM, where an RMSE of 5.25 TECU was found. This improvement corresponds to a performance increase by 35.6%. The storm-time model outperforms the quiet-time model by 1.34 TECU, which corresponds to a performance increase by 28.4% from 4.72 to 3.38 TECU. The quiet-time model was trained with Carrington averaged TEC and, therefore, is ideal to be used as an input instead of the GIM derived 27-day median. We found an improvement by 0.8 TECU which corresponds to a performance increase by 17% from 4.72 to 3.92 TECU for the storm-time model using the quiet-time-model predicted TEC as an input compared to solely using the quiet-time model.
KW  - ionosphere
KW  - relative total electron content
KW  - geomagnetic storms
KW  - neural
KW  - networks
KW  - NTCM
KW  - European storm-time model
Y1  - 2022
U6  - https://doi.org/10.3390/rs14236155
SN  - 2072-4292
VL  - 14
IS  - 23
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Agarwal, Ankit
A1  - Guntu, Ravikumar
A1  - Banerjee, Abhirup
A1  - Gadhawe, Mayuri Ashokrao
A1  - Marwan, Norbert
T1  - A complex network approach to study the extreme precipitation patterns in a river basin
JF  - Chaos : an interdisciplinary journal of nonlinear science
N2  - The quantification of spatial propagation of extreme precipitation events is vital in water resources planning and disaster mitigation. However, quantifying these extreme events has always been challenging as many traditional methods are insufficient to capture the nonlinear interrelationships between extreme event time series. Therefore, it is crucial to develop suitable methods for analyzing the dynamics of extreme events over a river basin with a diverse climate and complicated topography. Over the last decade, complex network analysis emerged as a powerful tool to study the intricate spatiotemporal relationship between many variables in a compact way. In this study, we employ two nonlinear concepts of event synchronization and edit distance to investigate the extreme precipitation pattern in the Ganga river basin. We use the network degree to understand the spatial synchronization pattern of extreme rainfall and identify essential sites in the river basin with respect to potential prediction skills. The study also attempts to quantify the influence of precipitation seasonality and topography on extreme events. The findings of the study reveal that (1) the network degree is decreased in the southwest to northwest direction, (2) the timing of 50th percentile precipitation within a year influences the spatial distribution of degree, (3) the timing is inversely related to elevation, and (4) the lower elevation greatly influences connectivity of the sites. The study highlights that edit distance could be a promising alternative to analyze event-like data by incorporating event time and amplitude and constructing complex networks of climate extremes.
Y1  - 2022
U6  - https://doi.org/10.1063/5.0072520
SN  - 1054-1500
SN  - 1089-7682
VL  - 32
IS  - 1
PB  - American Institute of Physics
CY  - Woodbury, NY
ER  - 
TY  - JOUR
A1  - Agarwal, Ankit
A1  - Maheswaran, Rathinasamy
A1  - Marwan, Norbert
A1  - Caesar, Levke
A1  - Kurths, Jürgen
T1  - Wavelet-based multiscale similarity measure for complex networks
JF  - The European physical journal : B, Condensed matter and complex systems
N2  - In recent years, complex network analysis facilitated the identification of universal and unexpected patterns in complex climate systems. However, the analysis and representation of a multiscale complex relationship that exists in the global climate system are limited. A logical first step in addressing this issue is to construct multiple networks over different timescales. Therefore, we propose to apply the wavelet multiscale correlation (WMC) similarity measure, which is a combination of two state-of-the-art methods, viz. wavelet and Pearson’s correlation, for investigating multiscale processes through complex networks. Firstly we decompose the data over different timescales using the wavelet approach and subsequently construct a corresponding network by Pearson’s correlation. The proposed approach is illustrated and tested on two synthetics and one real-world example. The first synthetic case study shows the efficacy of the proposed approach to unravel scale-specific connections, which are often undiscovered at a single scale. The second synthetic case study illustrates that by dividing and constructing a separate network for each time window we can detect significant changes in the signal structure. The real-world example investigates the behavior of the global sea surface temperature (SST) network at different timescales. Intriguingly, we notice that spatial dependent structure in SST evolves temporally. Overall, the proposed measure has an immense potential to provide essential insights on understanding and extending complex multivariate process studies at multiple scales.
KW  - Statistical and Nonlinear Physics
Y1  - 2018
U6  - https://doi.org/10.1140/epjb/e2018-90460-6
SN  - 1434-6028
SN  - 1434-6036
VL  - 91
IS  - 11
PB  - Springer
CY  - New York
ER  - 
TY  - THES
A1  - Ahlers, Volker
T1  - Scaling and synchronization in deterministic and stochastic nonlinear dynamical systems
N2  - Gegenstand dieser Arbeit ist die Untersuchung universeller Skalengesetze, die in gekoppelten chaotischen Systemen beobachtet werden. Ergebnisse werden erzielt durch das Ersetzen der chaotischen Fluktuationen in der Störungsdynamik durch stochastische Prozesse.   Zunächst wird ein zeitkontinuierliches stochastisches Modell fürschwach gekoppelte chaotische Systeme eingeführt, um die Skalierung der Lyapunov-Exponenten mit der Kopplungsstärke (coupling sensitivity of chaos) zu untersuchen. Mit Hilfe der Fokker-Planck-Gleichung werden Skalengesetze hergeleitet, die von Ergebnissen numerischer Simulationen bestätigt werden.   Anschließend wird der neuartige Effekt der vermiedenen Kreuzung von Lyapunov-Exponenten schwach gekoppelter ungeordneter chaotischer Systeme beschrieben, der qualitativ der Abstoßung zwischen Energieniveaus in Quantensystemen ähnelt. Unter Benutzung der für die coupling sensitivity of chaos gewonnenen Skalengesetze wird ein asymptotischer Ausdruck für die Verteilungsfunktion kleiner Abstände zwischen Lyapunov-Exponenten hergeleitet und mit Ergebnissen numerischer Simulationen verglichen.  Schließlich wird gezeigt, dass der Synchronisationsübergang in starkgekoppelten räumlich ausgedehnten chaotischen Systemen einem kontinuierlichen Phasenübergang entspricht, mit der Kopplungsstärke und dem Synchronisationsfehler als Kontroll- beziehungsweise Ordnungsparameter. Unter Benutzung von Ergebnissen numerischer Simulationen sowie theoretischen Überlegungen anhand einer partiellen Differentialgleichung mit multiplikativem Rauschen werden die Universalitätsklassen der zwei beobachteten Übergangsarten bestimmt (Kardar-Parisi-Zhang-Gleichung mit Sättigungsterm, gerichtete Perkolation).
N2  - Subject of this work is the investigation of universal scaling laws which are observed in coupled chaotic systems. Progress is made by replacing the chaotic fluctuations in the perturbation dynamics by stochastic processes.   First, a continuous-time stochastic model for weakly coupled chaotic systems is introduced to study the scaling of the Lyapunov exponents with the coupling strength (coupling sensitivity of chaos). By means of the the Fokker-Planck equation scaling relations are derived, which are confirmed by results of numerical simulations.   Next, the new effect of avoided crossing of Lyapunov exponents of weakly coupled disordered chaotic systems is described, which is qualitatively similar to the energy level repulsion in quantum systems. Using the scaling relations obtained for the coupling sensitivity of chaos, an asymptotic expression for the distribution function of small spacings between Lyapunov exponents is derived and compared with results of numerical simulations.   Finally, the synchronization transition in strongly coupled spatially extended chaotic systems is shown to resemble a continuous phase transition, with the coupling strength and the synchronization error as control and order parameter, respectively. Using results of numerical simulations and theoretical considerations in terms of a multiplicative noise partial differential equation, the universality classes of the observed two types of transition are determined (Kardar-Parisi-Zhang equation with saturating term, directed percolation).
KW  - Nichtlineare Dynamik
KW  - Chaostheorie
KW  - Stochastische Prozesse
KW  - Synchronisation
KW  - nonlinear dynamics
KW  - chaos
KW  - stochastic processes
KW  - synchronization
Y1  - 2001
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-0000320
ER  - 
TY  - JOUR
A1  - Ahnen, M. L.
A1  - Ansoldi, S.
A1  - Antonelli, L. A.
A1  - Antoranz, P.
A1  - Babic, A.
A1  - Banerjee, B.
A1  - Bangale, P.
A1  - de Almeida, U. Barres
A1  - Barrio, J. A.
A1  - Gonzalez, J. Becerra
A1  - Bednarek, W.
A1  - Bernardini, E.
A1  - Berti, A.
A1  - Biasuzzi, B.
A1  - Biland, A.
A1  - Blanch, O.
A1  - Bonnefoy, S.
A1  - Bonnoli, G.
A1  - Borracci, F.
A1  - Bretz, T.
A1  - Buson, S.
A1  - Carosi, A.
A1  - Chatterjee, A.
A1  - Clavero, R.
A1  - Colin, P.
A1  - Colombo, E.
A1  - Contreras, J. L.
A1  - Cortina, J.
A1  - Covino, S.
A1  - Da Vela, P.
A1  - Dazzi, F.
A1  - De Angelis, A.
A1  - De Lotto, B.
A1  - Wilhelmi, E. de Ona
A1  - Di Pierro, F.
A1  - Doert, M.
A1  - Dominguez, A.
A1  - Prester, D. Dominis
A1  - Dorner, D.
A1  - Doro, M.
A1  - Einecke, S.
A1  - Glawion, D. Eisenacher
A1  - Elsaesser, D.
A1  - Engelkemeier, M.
A1  - Ramazani, V. Fallah
A1  - Fernandez-Barral, A.
A1  - Fidalgo, D.
A1  - Fonseca, M. V.
A1  - Font, L.
A1  - Frantzen, K.
A1  - Fruck, C.
A1  - Galindo, D.
A1  - Lopez, R. J. Garcia
A1  - Garczarczyk, M.
A1  - Terrats, D. Garrido
A1  - Gaug, M.
A1  - Giammaria, P.
A1  - Godinovic, N.
A1  - Gonzalez Munoz, A.
A1  - Gora, D.
A1  - Guberman, D.
A1  - Hadasch, D.
A1  - Hahn, A.
A1  - Hanabata, Y.
A1  - Hayashida, M.
A1  - Herrera, J.
A1  - Hose, J.
A1  - Hrupec, D.
A1  - Hughes, G.
A1  - Idec, W.
A1  - Kodani, K.
A1  - Konno, Y.
A1  - Kubo, H.
A1  - Kushida, J.
A1  - La Barbera, A.
A1  - Lelas, D.
A1  - Lindfors, E.
A1  - Lombardi, S.
A1  - Longo, F.
A1  - Lopez, M.
A1  - Lopez-Coto, R.
A1  - Majumdar, P.
A1  - Makariev, M.
A1  - Mallot, K.
A1  - Maneva, G.
A1  - Manganaro, M.
A1  - Mannheim, K.
A1  - Maraschi, L.
A1  - Marcote, B.
A1  - Mariotti, M.
A1  - Martinez, M.
A1  - Mazin, D.
A1  - Menzel, U.
A1  - Miranda, J. M.
A1  - Mirzoyan, R.
A1  - Moralejo, A.
A1  - Moretti, E.
A1  - Nakajima, D.
A1  - Neustroev, V.
A1  - Niedzwiecki, A.
A1  - Rosillo, M. Nievas
A1  - Nilsson, K.
A1  - Nishijima, K.
A1  - Noda, K.
A1  - Nogues, L.
A1  - Overkemping, A.
A1  - Paiano, S.
A1  - Palacio, J.
A1  - Palatiello, M.
A1  - Paneque, D.
A1  - Paoletti, R.
A1  - Paredes, J. M.
A1  - Paredes-Fortuny, X.
A1  - Pedaletti, G.
A1  - Peresano, M.
A1  - Perri, L.
A1  - Persic, M.
A1  - Poutanen, J.
A1  - Moroni, P. G. Prada
A1  - Prandini, E.
A1  - Puljak, I.
A1  - Reichardt, I.
A1  - Rhode, W.
A1  - Ribo, M.
A1  - Rico, J.
A1  - Rodriguez Garcia, J.
A1  - Saito, T.
A1  - Satalecka, K.
A1  - Schroder, S.
A1  - Schultz, C.
A1  - Schweizer, T.
A1  - Shore, S. N.
A1  - Sillanpaa, A.
A1  - Sitarek, J.
A1  - Snidaric, I.
A1  - Sobczynska, D.
A1  - Stamerra, A.
A1  - Steinbring, T.
A1  - Strzys, M.
A1  - Suric, T.
A1  - Takalo, L.
A1  - Tavecchio, F.
A1  - Temnikov, P.
A1  - Terzic, T.
A1  - Tescaro, D.
A1  - Teshima, M.
A1  - Thaele, J.
A1  - Torres, D. F.
A1  - Toyama, T.
A1  - Treves, A.
A1  - Vanzo, G.
A1  - Verguilov, V.
A1  - Vovk, I.
A1  - Ward, J. E.
A1  - Will, M.
A1  - Wu, M. H.
A1  - Zanin, R.
A1  - Abeysekara, A. U.
A1  - Archambault, S.
A1  - Archer, A.
A1  - Benbow, W.
A1  - Bird, R.
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Dickinson, H. J.
A1  - Falcone, A.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fleischhack, H.
A1  - Flinders, A.
A1  - Fortson, L.
A1  - Gillanders, G. H.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Huetten, M.
A1  - Hanna, D.
A1  - Holder, J.
A1  - Humensky, T. B.
A1  - Kaaret, P.
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krause, M.
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - Maier, G.
A1  - McCann, A.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nieto, D.
A1  - Ong, R. A.
A1  - Otte, N.
A1  - Park, N.
A1  - Perkins, J.
A1  - Pichel, A.
A1  - Pohl, M.
A1  - Popkow, A.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rovero, A. C.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Telezhinsky, Igor O.
A1  - Tucci, J. V.
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Zitzer, B.
A1  - Razzaque, S.
A1  - Villata, M.
A1  - Raiteri, C. M.
A1  - Aller, H. D.
A1  - Aller, M. F.
A1  - Larionov, V. M.
A1  - Arkharov, A. A.
A1  - Blinov, D. A.
A1  - Efimova, N. V.
A1  - Grishina, T. S.
A1  - Hagen-Thorn, V. A.
A1  - Kopatskaya, E. N.
A1  - Larionova, L. V.
A1  - Larionova, E. G.
A1  - Morozova, D. A.
A1  - Troitsky, I. S.
A1  - Ligustri, R.
A1  - Calcidese, P.
A1  - Berdyugin, A.
A1  - Kurtanidze, O. M.
A1  - Nikolashvili, M. G.
A1  - Kimeridze, G. N.
A1  - Sigua, L. A.
A1  - Kurtanidze, S. O.
A1  - Chigladze, R. A.
A1  - Chen, W. P.
A1  - Koptelova, E.
A1  - Sakamoto, T.
A1  - Sadun, A. C.
A1  - Moody, J. W.
A1  - Pace, C.
A1  - Pearson, R.
A1  - Yatsu, Y.
A1  - Mori, Y.
A1  - Carraminyana, A.
A1  - Carrasco, L.
A1  - de la Fuente, E.
A1  - Norris, J. P.
A1  - Smith, P. S.
A1  - Wehrle, A.
A1  - Gurwell, M. A.
A1  - Zook, A.
A1  - Pagani, C.
A1  - Perri, M.
A1  - Capalbi, M.
A1  - Cesarini, A.
A1  - Krimm, H. A.
A1  - Kovalev, Y. Y.
A1  - Kovalev, Yu. A.
A1  - Ros, E.
A1  - Pushkarev, A. B.
A1  - Lister, M. L.
A1  - Sokolovsky, K. V.
A1  - Kadler, M.
A1  - Piner, G.
A1  - Lahteenmaki, A.
A1  - Tornikoski, M.
A1  - Angelakis, E.
A1  - Krichbaum, T. P.
A1  - Nestoras, I.
A1  - Fuhrmann, L.
A1  - Zensus, J. A.
A1  - Cassaro, P.
A1  - Orlati, A.
A1  - Maccaferri, G.
A1  - Leto, P.
A1  - Giroletti, M.
A1  - Richards, J. L.
A1  - Max-Moerbeck, W.
A1  - Readhead, A. C. S.
T1  - Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Aims. We present an extensive study of the BL Lac object Mrk 501 based on a data set collected during the multi-instrument campaign spanning from 2009 March 15 to 2009 August 1, which includes, among other instruments, MAGIC, VERITAS, Whipple 10 m, and Fermi-LAT to cover the gamma-ray range from 0.1 GeV to 20 TeV; RXTE and Swift to cover wavelengths from UV to hard X-rays; and GASP-WEBT, which provides coverage of radio and optical wavelengths. Optical polarization measurements were provided for a fraction of the campaign by the Steward and St. Petersburg observatories. We evaluate the variability of the source and interband correlations, the gamma-ray flaring activity occurring in May 2009, and interpret the results within two synchrotron self-Compton (SSC) scenarios. Methods. The multiband variability observed during the full campaign is addressed in terms of the fractional variability, and the possible correlations are studied by calculating the discrete correlation function for each pair of energy bands where the significance was evaluated with dedicated Monte Carlo simulations. The space of SSC model parameters is probed following a dedicated grid-scan strategy, allowing for a wide range of models to be tested and offering a study of the degeneracy of model-to-data agreement in the individual model parameters, hence providing a less biased interpretation than the "single-curve SSC model adjustment" typically reported in the literature. Results. We find an increase in the fractional variability with energy, while no significant interband correlations of flux changes are found on the basis of the acquired data set. The SSC model grid-scan shows that the flaring activity around May 22 cannot be modeled adequately with a one-zone SSC scenario (using an electron energy distribution with two breaks), while it can be suitably described within a two (independent) zone SSC scenario. Here, one zone is responsible for the quiescent emission from the averaged 4.5-month observing period, while the other one, which is spatially separated from the first, dominates the flaring emission occurring at X-rays and very-high-energy (> 100 GeV, VHE) gamma-rays. The flaring activity from May 1, which coincides with a rotation of the electric vector polarization angle (EVPA), cannot be satisfactorily reproduced by either a one-zone or a two-independent-zone SSC model, yet this is partially affected by the lack of strictly simultaneous observations and the presence of large flux changes on sub-hour timescales (detected at VHE gamma rays). Conclusions. The higher variability in the VHE emission and lack of correlation with the X-ray emission indicate that, at least during the 4.5-month observing campaign in 2009, the highest energy (and most variable) electrons that are responsible for the VHE gamma rays do not make a dominant contribution to the similar to 1 keV emission. Alternatively, there could be a very variable component contributing to the VHE gamma-ray emission in addition to that coming from the SSC scenario. The studies with our dedicated SSC grid-scan show that there is some degeneracy in both the one-zone and the two-zone SSC scenarios probed, with several combinations of model parameters yielding a similar model-to-data agreement, and some parameters better constrained than others. The observed gamma-ray flaring activity, with the EVPA rotation coincident with the first gamma-ray flare, resembles those reported previously for low frequency peaked blazars, hence suggesting that there are many similarities in the flaring mechanisms of blazars with different jet properties.
KW  - BL Lacertae objects: individual: Markarian 501
KW  - methods: data analysis
Y1  - 2017
U6  - https://doi.org/10.1051/0004-6361/201629540
SN  - 1432-0746
VL  - 603
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - THES
A1  - Ahnert, Karsten
T1  - Compactons in strongly nonlinear lattices
T1  - Kompaktonen in stark nichtlinearen Gittern
N2  - In the present work, we study wave phenomena in strongly nonlinear lattices. Such lattices are characterized by the absence of classical linear waves. We demonstrate that compactons – strongly localized solitary waves with tails decaying faster than exponential – exist and that they play a major role in the dynamics of the system under consideration. We investigate compactons in different physical setups. One part deals with lattices of dispersively coupled limit cycle oscillators which find various applications in natural sciences such as Josephson junction arrays or coupled Ginzburg-Landau equations. Another part deals with Hamiltonian lattices. Here, a prominent example in which compactons can be found is the granular chain. In the third part, we study systems which are related to the discrete nonlinear Schrödinger equation describing, for example, coupled optical wave-guides or the dynamics of Bose-Einstein condensates in optical lattices. Our investigations are based on a numerical method to solve the traveling wave equation. This results in a quasi-exact solution (up to numerical errors) which is the compacton. Another ansatz which is employed throughout this work is the quasi-continuous approximation where the lattice is described by a continuous medium. Here, compactons are found analytically, but they are defined on a truly compact support. Remarkably, both ways give similar qualitative and quantitative results. Additionally, we study the dynamical properties of compactons by means of numerical simulation of the lattice equations. Especially, we concentrate on their emergence from physically realizable initial conditions as well as on their stability due to collisions. We show that the collisions are not exactly elastic but that a small part of the energy remains at the location of the collision. In finite lattices, this remaining part will then trigger a multiple scattering process resulting in a chaotic state.
N2  - In der hier vorliegenden Arbeit werden Wellenphänomene in stark nichtlinearen Gittern untersucht. Diese Gitter zeichnen sich vor allem durch die Abwesenheit von klassischen linearen Wellen aus. Es wird gezeigt, dass Kompaktonen – stark lokalisierte solitäre Wellen, mit Ausläufern welche schneller als exponentiell abfallen – existieren, und dass sie eine entscheidende Rolle in der Dynamik dieser Gitter spielen. Kompaktonen treten in verschiedenen diskreten physikalischen Systemen auf. Ein Teil der Arbeit behandelt dabei Gitter von dispersiv gekoppelten Oszillatoren, welche beispielsweise Anwendung in gekoppelten Josephsonkontakten oder gekoppelten Ginzburg-Landau-Gleichungen finden. Ein weiterer Teil beschäftigt sich mit Hamiltongittern, wobei die granulare Kette das bekannteste Beispiel ist, in dem Kompaktonen beobachtet werden können. Im dritten Teil werden Systeme, welche im Zusammenhang mit der Diskreten Nichtlinearen Schrödingergleichung stehen, studiert. Diese Gleichung beschreibt beispielsweise Arrays von optischen Wellenleitern oder die Dynamik von Bose-Einstein-Kondensaten in optischen Gittern. Das Studium der Kompaktonen basiert hier hauptsächlich auf dem numerischen Lösen der dazugehörigen Wellengleichung. Dies mündet in einer quasi-exakten Lösung, dem Kompakton, welches bis auf numerische Fehler genau bestimmt werden kann. Ein anderer Ansatz, der in dieser Arbeit mehrfach verwendet wird, ist die Approximation des Gitters durch ein kontinuierliches Medium. Die daraus resultierenden Kompaktonen besitzen einen im mathematischen Sinne kompakten Definitionsbereich. Beide Methoden liefern qualitativ und quantitativ gut übereinstimmende Ergebnisse. Zusätzlich werden die dynamischen Eigenschaften von Kompaktonen mit Hilfe von direkten numerischen Simulationen der Gittergleichungen untersucht. Dabei wird ein Hauptaugenmerk auf die Entstehung von Kompaktonen unter physikalisch realisierbaren Anfangsbedingungen und ihre Kollisionen gelegt. Es wird gezeigt, dass die Wechselwirkung nicht exakt elastisch ist, sondern dass ein Teil ihrer Energie an der Position der Kollision verharrt. In endlichen Gittern führt dies zu einem multiplen Streuprozess, welcher in einem chaotischen Zustand endet.
KW  - Gitterdynamik
KW  - Hamilton
KW  - Compacton
KW  - Soliton
KW  - granulare Kette
KW  - Lattice dynamics
KW  - Hamiltonian
KW  - Compacton
KW  - Soliton
KW  - Granular chain
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-48539
ER  - 
TY  - JOUR
A1  - Akimoto, Takuma
A1  - Cherstvy, Andrey G.
A1  - Metzler, Ralf
T1  - Ergodicity, rejuvenation, enhancement, and slow relaxation of diffusion in biased continuous-time random walks
JF  - Physical review : E, Statistical, nonlinear and soft matter physics
N2  - Bias plays an important role in the enhancement of diffusion in periodic potentials. Using the continuous-time random walk in the presence of a bias, we report on an interesting phenomenon for the enhancement of diffusion by the start of the measurement in a random energy landscape. When the variance of the waiting time diverges, in contrast to the bias-free case, the dynamics with bias becomes superdiffusive. In the superdiffusive regime, we find a distinct initial ensemble dependence of the diffusivity. Moreover, the diffusivity can be increased by the aging time when the initial ensemble is not in equilibrium. We show that the time-averaged variance converges to the corresponding ensemble-averaged variance; i.e., ergodicity is preserved. However, trajectory-to-trajectory fluctuations of the time-averaged variance decay unexpectedly slowly. Our findings provide a rejuvenation phenomenon in the superdiffusive regime, that is, the diffusivity for a nonequilibrium initial ensemble gradually increases to that for an equilibrium ensemble when the start of the measurement is delayed.
Y1  - 2018
U6  - https://doi.org/10.1103/PhysRevE.98.022105
SN  - 2470-0045
SN  - 2470-0053
VL  - 98
IS  - 2
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Akpo, Claudia
A1  - Weber, Edwin
A1  - Reiche, Jürgen
T1  - Synthesis, Langmuir and Langmuir-Blodgett film behaviour of new dendritic amphiphiles
JF  - New journal of chemistry
N2  - New amphiphilic compounds 1-9 that feature a construction with dendronized hydrophilic and hydrophobic segment groups connected to a specific aromatic or aliphatic spacer unit have been synthesized, following a modular building block strategy. The hydrophilic dendrons are typically branched elements with peripheral carboxylic groups, unlike the hydrophobic dendrons that contain peripheral alkyl chains as part of respective amide functions. The hydrophilic dendrons are in different generations of branching, while the hydrophobic dendrons are all in the first generation of branching (three terminal branching), but differ in the length of the alkyl chains, thus giving rise to designed structure and amphiphilic properties in the new compounds. The resulting surfactants are capable of forming well-defined Langmuir films of remarkable stability when spread from a solution onto an aqueous subphase. Nevertheless, specific packing behaviour and orientation of the amphiphilic molecules were found, depending on the molecular structure, as determined using analysis of the surface pressure-area (pi-A) isotherms. Langmuir-Blodgett transfer of the first monolayer from a pure water subphase to a clean silicon wafer proved possible for the amphiphiles of peripheral alkyl chain length C-12, while the amphiphiles with the longer alkyl chains failed, possibly due to the more rigid monolayers they form, impeding the transfer.
Y1  - 2006
U6  - https://doi.org/10.1039/b609645j
SN  - 1144-0546
SN  - 1369-9261
VL  - 30
SP  - 1820
EP  - 1833
PB  - RSC
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Alawashra, Mahmoud
A1  - Pohl, Martin
T1  - Suppression of the TeV Pair-beam-Plasma Instability by a Tangled Weak Intergalactic Magnetic Field
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We study the effect of a tangled sub-fG level intergalactic magnetic field (IGMF) on the electrostatic instability of a blazar-induced pair beam. Sufficiently strong IGMF may significantly deflect the TeV pair beams, which would reduce the flux of secondary cascade emission below the observational limits. A similar flux reduction may result from the electrostatic beam-plasma instability, which operates the best in the absence of IGMF. Considering IGMF with correlation lengths smaller than a kiloparsec, we find that weak magnetic fields increase the transverse momentum of the pair-beam particles, which dramatically reduces the linear growth rate of the electrostatic instability and hence the energy-loss rate of the pair beam. We show that the beam-plasma instability is eliminated as an effective energy-loss agent at a field strength three orders of magnitude below that needed to suppress the secondary cascade emission by magnetic deflection. For intermediate-strength IGMF, we do not know a viable process to explain the observed absence of GeV-scale cascade emission.
Y1  - 2022
U6  - https://doi.org/10.3847/1538-4357/ac5a4b
SN  - 0004-637X
SN  - 1538-4357
VL  - 929
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - THES
A1  - Albers, Nicole
T1  - On the relevance of adhesion : applications to Saturn's rings
T1  - Zur Relevanz von Teilchenadhäsion : Anwendung auf die Ringe des Saturn
N2  - Since their discovery in 1610 by Galileo Galilei, Saturn's rings continue to fascinate both experts and amateurs. Countless numbers of icy grains in almost Keplerian orbits reveal a wealth of structures such as ringlets, voids and gaps, wakes and waves, and many more. Grains are found to increase in size with increasing radial distance to Saturn. Recently discovered "propeller" structures in the Cassini spacecraft data, provide evidence for the existence of embedded moonlets. In the wake of these findings, the discussion resumes about origin and evolution of planetary rings, and growth processes in tidal environments. In this thesis, a contact model for binary adhesive, viscoelastic collisions is developed that accounts for agglomeration as well as restitution. Collisional outcomes are crucially determined by the impact speed and masses of the collision partners and yield a maximal impact velocity at which agglomeration still occurs. Based on the latter, a self-consistent kinetic concept is proposed. The model considers all possible collisional outcomes as there are coagulation, restitution, and fragmentation. Emphasizing the evolution of the mass spectrum and furthermore concentrating on coagulation alone, a coagulation equation, including a restricted sticking probability is derived. The otherwise phenomenological Smoluchowski equation is reproduced from basic principles and denotes a limit case to the derived coagulation equation. Qualitative and quantitative analysis of the relevance of adhesion to force-free granular gases and to those under the influence of Keplerian shear is investigated. Capture probability, agglomerate stability, and the mass spectrum evolution are investigated in the context of adhesive interactions. A size dependent radial limit distance from the central planet is obtained refining the Roche criterion. Furthermore, capture probability in the presence of adhesion is generally different compared to the case of pure gravitational capture. In contrast to a Smoluchowski-type evolution of the mass spectrum, numerical simulations of the obtained coagulation equation revealed, that a transition from smaller grains to larger bodies cannot occur via a collisional cascade alone. For parameters used in this study, effective growth ceases at an average size of centimeters.
N2  - Seit ihrer Entdeckung im Jahre 1610 durch Galileo Galilei faszinieren die Ringe des Saturn sowohl Laien als auch Experten. Planetare Ringe finden sich in der Äquatorialebene aller vier Riesenplaneten unseres Sonnensystems und sind eines der eindruckvollsten Beispiele granularer Gase. Darunter gehören die Saturnringe zu den Bekanntesten. Sie bergen eine Vielzahl von Strukturen und erstrecken sich über mehr als 240 000 Kilometer, wobei sie weit weniger als 100 Meter dick sind. Unzählige kleinerer Körper bewegen sich auf leicht exzentrischen Kepler-ähnlichen Bahnen um den Zentralplaneten und bestehen dabei vorwiegend aus Eis. Die seit Juli 2004 im Orbit um den Saturn befindliche Raumsonde Cassini liefert atemberaubende Bilder und Daten, die nicht nur neue Erkenntnisse liefern, sondern auch alte Fragestellungen neu aufleben lassen. Dazu gehört z.B. die Frage nach dem Ursprung und den Entwicklungsstufen planetarer Ringe. Kürzlich, im äusseren A-Ring entdeckte Kleinmonde, deren Existenz schon viel früher postuliert wurde, weisen auf eventuell stattfindende Wachstumsprozesse hin. Da sich planetare Ringe jedoch hauptsächlich innerhalb der sogenannten Roche-Zone des jeweiligen Planeten befinden, ist ein effektives, allein auf gravitativen Wechselwirkungen beruhendes Größenwachstum nicht zu erwarten. Der Einfluß von Teilchenadhäsion auf diese Prozesse ist bis dato fraglich. Im Rahmen dieser Dissertation ist ein Kontaktmodell für adhäsive, viskoelastische Binärstöße granularer Teilchen entwickelt worden, welches sowohl deren Agglomeration als auch Restitution gestattet. Chakateristisch für granulare Materie ist die dissipative Wechselwirkung der einzelnen Teilchen untereinander. Dieser Energieverlust wird gewöhnlich mittels des Restitutionskoeffizienten erfaßt, der das Verhältnis von Relativgeschwindigkeiten nach zu vor dem Stoß darstellt. Dieser Parameter ermöglicht es, Agglomeration und Restitution nicht nur qualitativ sondern auch quantitativ voneinander zu unterscheiden. Ferner ergibt sich eine maximale Impaktgeschwindigkeit, bei der eine Agglomeration noch immer möglich ist. Basierend auf der Existenz derartiger Grenzgeschwindigkeiten für Agglomeration und Fragmentation, wurde in dieser Dissertation ein selbstkonsistentes, kinetisches Strukturbildungsmodell vorgestellt und im Hinblick auf die Koagulation von Teilchen weitergehend untersucht. Eine Koagulationsgleichung, die einer eingeschränkten Haftwahrscheinlichkeit Rechnung trägt, ist analytisch hergeleitet worden. Aus ihr läßt sich die allgemein bekannte, aber ansonsten phenomenologische Smoluchowski Gleichung als ein Grenzfall ableiten, bei dem jeder mögliche Kontakt zur Koagulation führt. Qualitative und quantitative Untersuchungen der Relevanz von Adhäsion in kräftefreien und Kepler-gescherten Systemen beziehen sich auf die Stabilität von Zwei-Teilchen-Agglomeraten, die Wahrscheinlichkeit eines gegenseitigen "Einfangens" beider Teilchen, und die zeitliche Entwicklung der Größenverteilung unter Berücksichtigung der im ersten Teil dieser Arbeit eingeführten Kollisionsdynamik. Dabei ergab sich ein kritischer Abstand zum Zentralkörper, der das ansonsten in diesem Rahmen benutzte Roche Kriterium erweitert. Numerische Simulationen der vorgestellten Koagulationsgleichung zeigen deutlich, daß im Vergleich zu Smoluchowski-ähnlichem Verhalten, ein kollisionsbasiertes Wachstum von kleineren zu größeren Körpern nicht notwendigerweise auftritt. Lediglich Größen von Zentimetern konnten an dieser Stelle erreicht werden. Die Relevanz von adhäsiven Teilchenwechselwirkungen konnte damit nachgewiesen werden. Vermögen diese auch nicht für ein effektives Wachstum aufzukommen, so sind sie dennoch von Bedeutung für die kollektive Dynamik planetarer Ringe.
KW  - Saturn<Planet>
KW  - Cassini<Raumsonde>
KW  - Adhäsion
KW  - Kinetik
KW  - Planetare Ringe
KW  - Roche Limit
KW  - Roche
KW  - Agglomeration
KW  - Kollisionsdynamik
KW  - planetary rings
KW  - Saturn
KW  - collision dynamics
KW  - adhesion
KW  - kinetics
KW  - kinetic
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-10848
ER  - 
TY  - THES
A1  - Albrecht, Steve
T1  - Generation, recombination and extraction of charges in polymer
T1  - Generierung, Rekombination und Extraktion von Ladungen in Polymer
BT  - fullerene bulk heterojunction solar cells
BT  - Fulleren Mischsolarzellen
N2  - A dramatic efficiency improvement of bulk heterojunction solar cells based on electron-donating conjugated polymers in combination with soluble fullerene derivatives has been achieved over the past years. Certified and reported power conversion efficiencies now reach over 9% for single junctions and exceed the 10% benchmark for tandem solar cells. This trend brightens the vision of organic photovoltaics becoming competitive with inorganic solar cells including the realization of low-cost and large-area organic photovoltaics. For the best performing organic materials systems, the yield of charge generation can be very efficient. However, a detailed understanding of the free charge carrier generation mechanisms at the donor acceptor interface and the energy loss associated with it needs to be established. Moreover, organic solar cells are limited by the competition between charge extraction and free charge recombination, accounting for further efficiency losses. A conclusive picture and the development of precise methodologies for investigating the fundamental processes in organic solar cells are crucial for future material design, efficiency optimization, and the implementation of organic solar cells into commercial products.
In order to advance the development of organic photovoltaics, my thesis focuses on the comprehensive understanding of charge generation, recombination and extraction in organic bulk heterojunction solar cells summarized in 6 chapters on the cumulative basis of 7 individual publications. 
The general motivation guiding this work was the realization of an efficient hybrid inorganic/organic tandem solar cell with sub-cells made from amorphous hydrogenated silicon and organic bulk heterojunctions. To realize this project aim, the focus was directed to the low band-gap copolymer PCPDTBT and its derivatives, resulting in the examination of the charge carrier dynamics in PCPDTBT:PC70BM blends in relation to by the blend morphology. The phase separation in this blend can be controlled by the processing additive diiodooctane, enhancing domain purity and size. The quantitative investigation of the free charge formation was realized by utilizing and improving the time delayed collection field technique. Interestingly, a pronounced field dependence of the free carrier generation for all blends is found, with the field dependence being stronger without the additive. Also, the bimolecular recombination coefficient for both blends is rather high and increases with decreasing internal field which we suggest to be caused by a negative field dependence of mobility. The additive speeds up charge extraction which is rationalized by the threefold increase in mobility.
By fluorine attachment within the electron deficient subunit of PCPDTBT, a new polymer F-PCPDTBT is designed. This new material is characterized by a stronger tendency to aggregate as compared to non-fluorinated PCPDTBT. Our measurements show that for F-PCPDTBT:PCBM blends the charge carrier generation becomes more efficient and the field-dependence of free charge carrier generation is weakened. The stronger tendency to aggregate induced by the fluorination also leads to increased polymer rich domains, accompanied in a threefold reduction in the non-geminate recombination coefficient at conditions of open circuit. The size of the polymer domains is nicely correlated to the field-dependence of charge generation and the Langevin reduction factor, which highlights the importance of the domain size and domain purity for efficient charge carrier generation. In total, fluorination of PCPDTBT causes the PCE to increase from 3.6 to 6.1% due to enhanced fill factor, short circuit current and open circuit voltage. Further optimization of the blend ratio, active layer thickness, and polymer molecular weight resulted in 6.6% efficiency for F-PCPDTBT:PC70BM solar cells.
Interestingly, the double fluorinated version 2F-PCPDTBT exhibited poorer FF despite a further reduction of geminate and non-geminate recombination losses. To further analyze this finding, a new technique is developed that measures the effective extraction mobility under charge carrier densities and electrical fields comparable to solar cell operation conditions. This method involves the bias enhanced charge extraction technique. With the knowledge of the carrier density under different electrical field and illumination conditions, a conclusive picture of the changes in charge carrier dynamics leading to differences in the fill factor upon fluorination of PCPDTBT is attained. The more efficient charge generation and reduced recombination with fluorination is counterbalanced by a decreased extraction mobility. Thus, the highest fill factor of 60% and efficiency of 6.6% is reached for F-PCPDTBT blends, while 2F-PCPDTBT blends have only moderate fill factors of 54% caused by the lower effective extraction mobility, limiting the efficiency to 6.5%. 
To understand the details of the charge generation mechanism and the related losses, we evaluated the yield and field-dependence of free charge generation using time delayed collection field in combination with sensitive measurements of the external quantum efficiency and absorption coefficients for a variety of blends. Importantly, both the yield and field-dependence of free charge generation is found to be unaffected by excitation energy, including direct charge transfer excitation below the optical band gap. To access the non-detectable absorption at energies of the relaxed charge transfer emission, the absorption was reconstructed from the CT emission, induced via the recombination of thermalized charges in electroluminescence. For a variety of blends, the quantum yield at energies of charge transfer emission was identical to excitations with energies well above the optical band-gap. Thus, the generation proceeds via the split-up of the thermalized charge transfer states in working solar cells. Further measurements were conducted on blends with fine-tuned energy levels and similar blend morphologies by using different fullerene derivatives. A direct correlation between the efficiency of free carrier generation and the energy difference of the relaxed charge transfer state relative to the energy of the charge separated state is found. These findings open up new guidelines for future material design as new high efficiency materials require a minimum energetic offset between charge transfer and the charge separated state while keeping the HOMO level (and LUMO level) difference  between donor and acceptor as small as possible.
N2  - Die Effizienz von organischen Mischsolarzellen ist in den letzten Jahren durch die Entwicklung neuer halbleitender Materialen beträchtlich gestiegen. Die besten organischen Mischsolarzellen zeigen heute sehr effiziente Ladungsgeneration. Dennoch ist die genaue Funktionsweise der fundamentalen Ladungsgenerationsschritte nicht bis ins Detail verstanden. Zur weiteren Steigerung der Wirkungsgrade und für die kommerzielle Nutzung organischer Mischsolarzellen, sind ein übergreifendes Verständnis der Funktionsweise und die Entwicklung neuer Messmethoden unumgänglich. Die vorliegende Arbeit ist auf diese Fragestellung fokussiert: die Arbeit soll helfen, fundierte Kenntnisse der Ladungsträgererzeugung, der Rekombination und der Extraktion freier Ladungsträger in organischen Mischsolarzellen zu erlangen. 
Zuerst wurde der Fokus auf Mischsolarzellen mit dem Polymer PCPDTBT gelegt. Dieses Polymer durchmischt stark mit dem Fulleren-Derivat PCBM. Durch Verwendung eines Lösungsmitteladditives kann die Phasenentmischung und damit der Wirkungsgrad deutlich gesteigert werden. Die Generations- und Rekombinationsprozesse wurden mittels zeitverzögerter Sammelfeld-Methode untersucht. Dabei wurde zum ersten Mal eine signifikante Feldabhängigkeit der Ladungsträger-erzeugung entdeckt. Interessanterweise korreliert diese Feldabhängigkeit mit der Domänengröße also dem Grad der Entmischung. In größeren und reineren Polymerphasen ist die Feldabhängigkeit kleiner und die Extraktion verbessert,  was zum höheren Wirkungsgrad führt. 
In einem weiteren Schritt wurde untersucht, wie sich die Fluorinierung des Polymers PCPDTBT auf das Bauteilverhalten auswirkt. Durch Fluorinierung des Polymer-Rückgrats von PCPDTBT wurden zum einen die Energieniveaus abgesenkt, ohne dass sich das Absorptionsverhalten geändert hat. Zum anderen wurde die Phasenentmischung beeinflusst. Mit Fluorinierung entstehen größere, reinere und kristallinere Polymerphasen. Dadurch  wird die Generation der Ladungsträger effizienter und die Rekombination stärker unterdrückt. Eindeutige Korrelationen zwischen Phasengröße und Generationseffizienz konnten hierbei gefunden werden. Insgesamt steigt die Bauteileffizienz bei Verwendung von fluoriniertem PCPDTBT von 3.6 auf 6.1% bei gleicher Prozessierung. Durch weitere Optimierung konnte die Effizienz auf 6.6% für fluoriniertes PCPDTBT gesteigert werden. 
Eine di-Fluorinierung von PCPDTBT limitiert die Bauteileffizienz, speziell den Füll Faktor, trotz der Entstehung noch reinerer Polymerphasen. Eine genauere Analyse der Extraktionseffizienz mittels der genauen Bestimmung der Gleichgewichts-Ladungsträgerdichte für verschiedenen Beleuchtungs- und Feldsituationen zeigte, dass die Fluorinierung die Effizienz der Extraktion deutlich absenkt und dadurch bei di-Fluorinierung die Rekombinationsverluste im Bauteil trotz verlangsamter Rekombination ansteigen.
Um weitere fundierte Kenntnisse der Ladungsgeneration zu gewinnen, wurde die Ladungsgeneration für verschiedene Gemische mit veränderten Energieniveaus in Abhängigkeit der Anregungsenergie untersucht. Dabei wurde die wichtige Kenntnis erlangt, dass die Photonenenergie, unabhängig von der Lage der Energieniveaus, keinen Einfluss auf die Effizienz der Generation hat und somit die Bildung freier Ladungsträger aus relaxierten Transferzuständen erfolgt. Dadurch ergeben sich neue Leitlinien für zukünftige Materialeigenschaften mit optimierten Wirkungsgraden.
KW  - organic solar cells
KW  - bulk heterojunction
KW  - charge carrier dynamics
KW  - charge generation
KW  - non geminate recombination
KW  - Generierung von Ladungsträgern
KW  - nicht geminale Rekombination
KW  - Extraktion
KW  - Polymer
KW  - Fulleren
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-72285
ER  - 
TY  - JOUR
A1  - Albrecht, Torsten
A1  - Winkelmann, Ricarda
A1  - Levermann, Anders
T1  - Glacial-cycle simulations of the Antarctic Ice Sheet with the Parallel Ice Sheet Model (PISM)
BT  - part 2: parameter ensemble analysis
JF  - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2  - The Parallel Ice Sheet Model (PISM) is applied to the Antarctic Ice Sheet over the last two glacial cycles (approximate to 210 000 years) with a resolution of 16 km. An ensemble of 256 model runs is analyzed in which four relevant model parameters have been systematically varied using full-factorial parameter sampling. Parameters and plausible parameter ranges have been identified in a companion paper (Albrecht et al., 2020) and are associated with ice dynamics, climatic forcing, basal sliding and bed deformation and represent distinct classes of model uncertainties. The model is scored against both modern and geologic data, including reconstructed grounding-line locations, elevation-age data, ice thickness, surface velocities and uplift rates. An aggregated score is computed for each ensemble member that measures the overall model-data misfit, including measurement uncertainty in terms of a Gaussian error model (Briggs and Tarasov, 2013). The statistical method used to analyze the ensemble simulation results follows closely the simple averaging method described in Pollard et al. (2016). 
This analysis reveals clusters of best-fit parameter combinations, and hence a likely range of relevant model and boundary parameters, rather than individual best-fit parameters. The ensemble of reconstructed histories of Antarctic Ice Sheet volumes provides a score-weighted likely range of sea-level contributions since the Last Glacial Maximum (LGM) of 9.4 +/- 4.1m (or 6.5 +/- 2.0 x 10(6) km(3)), which is at the upper range of most previous studies. The last deglaciation occurs in all ensemble simulations after around 12 000 years before present and hence after the meltwater pulse 1A (MWP1a). Our ensemble analysis also provides an estimate of parametric uncertainty bounds for the present-day state that can be used for PISM projections of future sea-level contributions from the Antarctic Ice Sheet.
Y1  - 2020
U6  - https://doi.org/10.5194/tc-14-633-2020
SN  - 1994-0416
SN  - 1994-0424
VL  - 14
IS  - 2
SP  - 633
EP  - 656
PB  - Copernicus Publ.
CY  - Göttingen
ER  - 
TY  - THES
A1  - Albus, Alexander P.
T1  - Mixtures of Bosonic and Fermionic atoms
N2  - Ziel der Arbeit war die systematische theoretische Behandlung von Gemischen aus bosonischen und fermionischen Atomen in einem Parameterbereich, der sich zur Beschreibung von aktuellen Experimenten mit ultra-kalten atomaren Gasen eignet.  Zuerst wurde der Formalismus der Quantenfeldtheorie auf homogene, atomare Boson-Fermion Gemische erweitert, um grundlegende Größen wie Quasiteilchenspektren, die Grundzustandsenergie und daraus abgeleitete Größen über die Molekularfeldtheorie hinaus zu berechnen.  Unter Zuhilfenahme der dieser Resultate System wurde ein Boson-Fermion Gemisch in einem Fallenpotential im Rahmen der Dichtefunktionaltheorie beschrieben. Daraus konnten die Dichteprofile ermittelt werden und es ließen sich drei Bereiche im Phasendiagramm identifizieren:  (i) ein Bereich eines stabilen Gemisches, (ii) ein Bereich, in dem die Spezies entmischt sind und  (iii) ein Bereich, in dem das System kollabiert.  Im letzten dieser drei Fällen waren Austausch--Korrelationseffekte signifikant. Weiterhin wurde die Änderung der kritischen Temperatur der Bose-Einstein-Kondensation aufgrund der Boson-Fermion-Wechselwirkung berechnet. Verursacht wird dieser Effekt von Dichtumverteilungen aufgrund der Wechselwirkung.  Dann wurden Boson-Fermion Gemische in optischen Gittern betrachtet. Ein Stabilitätskriterium gegen Phasenentmischung wurde gefunden und es ließen sich Bedingungen für einen supraflüssig zu Mott-isolations Phasenübergang angeben. Diese wurden sowohl mittels einer Molekularfeldrechnung als auch numerisch im Rahmen eines Gutzwilleransatzes gefunden. Es wurden weiterhin neuartige frustrierte Grundzustände im Fall von sehr großen Gitterstärken gefunden.
N2  - The theory of atomic Boson-Fermion mixtures in the dilute limit beyond mean-field is considered in this thesis. Extending the formalism of quantum field theory we derived expressions for the quasi-particle excitation spectra, the ground state energy, and related quantities for a homogenous system to first order in the dilute gas parameter.  In the framework of density functional theory we could carry over the previous results to inhomogeneous systems. We then determined to density distributions for various parameter values and identified three different phase regions:  (i) a stable mixed regime,  (ii) a phase separated regime, and  (iii) a collapsed regime.   We found a significant contribution of exchange-correlation effects in the latter case. Next, we determined the shift of the Bose-Einstein condensation temperature caused by Boson-Fermion interactions in a harmonic trap due to redistribution of the density profiles.  We then considered Boson-Fermion mixtures in optical lattices. We calculated the criterion for stability against phase separation, identified the Mott-insulating and superfluid regimes both, analytically within a mean-field calculation, and numerically by virtue of a Gutzwiller Ansatz. We also found new frustrated ground states in the limit of very strong lattices. ----Anmerkung: Der Autor ist Träger des durch die Physikalische Gesellschaft zu Berlin vergebenen Carl-Ramsauer-Preises 2004 für die jeweils beste Dissertation der vier Universitäten Freie Universität Berlin, Humboldt-Universität zu Berlin, Technische Universität Berlin und Universität Potsdam.
KW  - Quantendegeneriert BEK FDS ultrakalte Atome
KW  - quantum degenerate BEC FDS ultacold atoms
Y1  - 2003
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-0001065
ER  - 
TY  - JOUR
A1  - Aldiyarov, Abdurakhman
A1  - Sokolov, Dmitriy
A1  - Akylbayeva, Aigerim
A1  - Nurmukan, Assel
A1  - Tokmoldin, Nurlan
T1  - On thermal stability of cryovacuum deposited CH4+H2O films
JF  - Low temperature physics
N2  - Whereas stable homogenous states of aqueous hydrocarbon solutions are typically observed at high temperatures and pressures far beyond the critical values corresponding to individual components, the stability of such system may be preserved upon transition into the region of metastable states at low temperatures and low pressures. This work is dedicated to the study of the thermal stability of a water-methane mixture formed by cryogenic vapor phase deposition. The obtained thin films were studied using vibrational spectroscopy in the temperature range of 16-180 K. During thermal annealing of the samples, characteristic vibrational C-H modes of methane were monitored alongside the chamber pressure to register both structural changes and desorption of the film material. The obtained results reveal that upon the co-deposition of methane and water, methane molecules appear both in non-bound and trapped states. The observed broadening of the characteristic C-H stretching mode at 3010 cm(-1) upon an increase in temperature of the sample from 16 to 90 K, followed by narrowing of the peak as the temperature is reduced back to 16 K, indicates localization of methane molecules within the water matrix at lower temperatures.
KW  - molecular crystals
KW  - water-methane films
KW  - vibrational spectroscopy
KW  - low
KW  - temperature
KW  - methane localization
Y1  - 2020
U6  - https://doi.org/10.1063/10.0002156
SN  - 1063-777X
SN  - 1090-6517
VL  - 46
IS  - 11
SP  - 1121
EP  - 1124
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - GEN
A1  - Alirezaeizanjani, Zahra
A1  - Großmann, Robert
A1  - Pfeifer, Veronika
A1  - Hintsche, Marius
A1  - Beta, Carsten
T1  - Chemotaxis strategies of bacteria with multiple run modes
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Bacterial chemotaxis-a fundamental example of directional navigation in the living world-is key to many biological processes, including the spreading of bacterial infections. Many bacterial species were recently reported to exhibit several distinct swimming modes-the flagella may, for example, push the cell body or wrap around it. How do the different run modes shape the chemotaxis strategy of a multimode swimmer? Here, we investigate chemotactic motion of the soil bacterium Pseudomonas putida as a model organism. By simultaneously tracking the position of the cell body and the configuration of its flagella, we demonstrate that individual run modes show different chemotactic responses in nutrition gradients and, thus, constitute distinct behavioral states. On the basis of an active particle model, we demonstrate that switching between multiple run states that differ in their speed and responsiveness provides the basis for robust and efficient chemotaxis in complex natural habitats.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1418 
KW  - instability
KW  - flagellum
KW  - exploit
KW  - time
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-519098
SN  - 1866-8372
IS  - 22
ER  - 
TY  - JOUR
A1  - Alirezaeizanjani, Zahra
A1  - Großmann, Robert
A1  - Pfeifer, Veronika
A1  - Hintsche, Marius
A1  - Beta, Carsten
T1  - Chemotaxis strategies of bacteria with multiple run modes
JF  - Science advances
N2  - Bacterial chemotaxis-a fundamental example of directional navigation in the living world-is key to many biological processes, including the spreading of bacterial infections. Many bacterial species were recently reported to exhibit several distinct swimming modes-the flagella may, for example, push the cell body or wrap around it. How do the different run modes shape the chemotaxis strategy of a multimode swimmer? Here, we investigate chemotactic motion of the soil bacterium Pseudomonas putida as a model organism. By simultaneously tracking the position of the cell body and the configuration of its flagella, we demonstrate that individual run modes show different chemotactic responses in nutrition gradients and, thus, constitute distinct behavioral states. On the basis of an active particle model, we demonstrate that switching between multiple run states that differ in their speed and responsiveness provides the basis for robust and efficient chemotaxis in complex natural habitats.
KW  - exploit
KW  - flagellum
KW  - instability
KW  - time
Y1  - 2020
U6  - https://doi.org/10.1126/sciadv.aaz6153
SN  - 2375-2548
VL  - 6
IS  - 22
PB  - American Association for the Advancement of Science
CY  - Washington
ER  - 
TY  - THES
A1  - Allefeld, Carsten
T1  - Phase synchronization analysis of event-related brain potentials in language processing
N2  - Das Forschungsthema Synchronisation bildet einen Schnittpunkt von Nichtlinearer Dynamik und Neurowissenschaft. So hat zum einen neurobiologische Forschung gezeigt, daß die Synchronisation neuronaler Aktivität einen wesentlichen Aspekt der Funktionsweise des Gehirns darstellt. Zum anderen haben Fortschritte in der physikalischen Theorie zur Entdeckung des Phänomens der Phasensynchronisation geführt. Eine dadurch motivierte Datenanalysemethode, die Phasensynchronisations-Analyse, ist bereits mit Erfolg auf empirische Daten angewandt worden. Die vorliegende Dissertation knüpft an diese konvergierenden Forschungslinien an. Ihren Gegenstand bilden methodische Beiträge zur Fortentwicklung der Phasensynchronisations-Analyse, sowie deren Anwendung auf ereigniskorrelierte Potentiale, eine besonders in den Kognitionswissenschaften wichtige Form von EEG-Daten. Die methodischen Beiträge dieser Arbeit bestehen zum ersten in einer Reihe spezialisierter statistischer Tests auf einen Unterschied der Synchronisationsstärke in zwei verschiedenen Zuständen eines Systems zweier Oszillatoren. Zweitens wird im Hinblick auf den viel-kanaligen Charakter von EEG-Daten ein Ansatz zur multivariaten Phasensynchronisations-Analyse vorgestellt. Zur empirischen Untersuchung neuronaler Synchronisation wurde ein klassisches Experiment zur Sprachverarbeitung repliziert, in dem der Effekt einer semantischen Verletzung im Satzkontext mit demjenigen der Manipulation physischer Reizeigenschaften (Schriftfarbe) verglichen wird. Hier zeigt die Phasensynchronisations-Analyse eine Verringerung der globalen Synchronisationsstärke für die semantische Verletzung sowie eine Verstärkung für die physische Manipulation. Im zweiten Fall läßt sich der global beobachtete Synchronisationseffekt mittels der multivariaten Analyse auf die Interaktion zweier symmetrisch gelegener Gehirnareale zurückführen. Die vorgelegten Befunde zeigen, daß die physikalisch motivierte Methode der Phasensynchronisations-Analyse einen wesentlichen Beitrag zur Untersuchung ereigniskorrelierter Potentiale in den Kognitionswissenschaften zu leisten vermag.
N2  - The topic of synchronization forms a link between nonlinear dynamics and neuroscience. On the one hand, neurobiological research has shown that the synchronization of neuronal activity is an essential aspect of the working principle of the brain. On the other hand, recent advances in the physical theory have led to the discovery of the phenomenon of phase synchronization. A method of data analysis that is motivated by this finding - phase synchronization analysis - has already been successfully applied to empirical data. The present doctoral thesis ties up to these converging lines of research. Its subject are methodical contributions to the further development of phase synchronization analysis, as well as its application to event-related potentials, a form of EEG data that is especially important in the cognitive sciences. The methodical contributions of this work consist firstly in a number of specialized statistical tests for a difference in the synchronization strength in two different states of a system of two oscillators. Secondly, in regard of the many-channel character of EEG data an approach to multivariate phase synchronization analysis is presented. For the empirical investigation of neuronal synchronization a classic experiment on language processing was replicated, comparing the effect of a semantic violation in a sentence context with that of the manipulation of physical stimulus properties (font color). Here phase synchronization analysis detects a decrease of global synchronization for the semantic violation as well as an increase for the physical manipulation. In the latter case, by means of the multivariate analysis the global synchronization effect can be traced back to an interaction of symmetrically located brain areas.<BR> The findings presented show that the method of phase synchronization analysis motivated by physics is able to provide a relevant contribution to the investigation of event-related potentials in the cognitive sciences.
T2  - Phase synchronization analysis of event-related brain potentials in language processing
KW  - Synchronisation
KW  - EEG
KW  - Sprachverarbeitung
KW  - Multivariate Analyse
KW  - synchronization
KW  - EEG
KW  - language processing
KW  - multivariate analysis
Y1  - 2004
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-0001873
ER  - 
TY  - GEN
A1  - Allefeld, Carsten
T1  - About the derivation of the SCA algorithm
N2  - In Allefeld & Kurths [2004], we introduced an approach to multivariate phase synchronization analysis in the form of a Synchronization Cluster Analysis (SCA). A statistical model of a synchronization cluster was described, and an abbreviated instruction on how to apply this model to empirical data was given, while an implementation of the corresponding algorithm was (and is) available from the authors. In this letter, the complete details on how the data analysis algorithm is to be derived from the model are filled in.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 075 
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-20137
ER  - 
TY  - GEN
A1  - Allefeld, Carsten
A1  - Frisch, Stefan
T1  - Phase synchronization analysis of event-related potentials in language processing
N2  - Phase synchronization analysis, including our recently introduced multivariate approach, is applied to event-related EEG data from an experiment on language processing, following a classic psycholinguistic paradigm. For the two types of experimental manipulation distinct effects in overall synchronization are found; for one of them they can also be localized. The synchronization effects occur earlier than those found by the conventional analysis method, indicating that the new approach provides additional information on the underlying neuronal process.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 073 
Y1  - 2004
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-20113
ER  - 
TY  - GEN
A1  - Allefeld, Carsten
A1  - Frisch, Stefan
A1  - Schlesewsky, Matthias
T1  - Detection of early cognitive processing by event-related phase synchronization analysis
N2  - In order to investigate the temporal characteristics of cognitive processing, we apply multivariate phase synchronization analysis to event-related potentials. The experimental design combines a semantic incongruity in a sentence context with a physical mismatch (color change). In the ERP average, these result in an N400 component and a P300-like positivity, respectively. The synchronization analysis shows an effect of global desynchronization in the theta band around 288ms after stimulus presentation for the semantic incongruity, while the physical mismatch elicits an increase of global synchronization in the alpha band around 204ms. Both of these effects clearly precede those in the ERP average. Moreover, the delay between synchronization effect and ERP component correlates with the complexity of the cognitive processes.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 074 
KW  - phase synchronization
KW  - coherence
KW  - semantic incongruity
KW  - color change
KW  - N400
KW  - P300
KW  - theta
KW  - alpha
Y1  - 2005
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-20126
ER  - 
TY  - GEN
A1  - Allefeld, Carsten
A1  - Kurths, Jürgen
T1  - Testing for phase synchronization
N2  - We present different tests for phase synchronization which improve the procedures currently used in the literature. This is accomplished by using a two-samples test setup and by utilizing insights and methods from directional statistics and bootstrap theory. The tests differ in the generality of the situation in which they can be applied as well as in their complexity, including computational cost. A modification of the resampling technique of the bootstrap is introduced, making it possible to fully utilize data from time series.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 071 
Y1  - 2004
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-20091
ER  - 
TY  - GEN
A1  - Allefeld, Carsten
A1  - Kurths, Jürgen
T1  - An approach to multivariate phase synchronization analysis and its application to event-related potentials
N2  - A method for the multivariate analysis of statistical phase synchronization phenomena in empirical data is presented. A first statistical approach is complemented by a stochastic dynamic model, to result in a data analysis algorithm which can in a specific sense be shown to be a generic multivariate statistical phase synchronization analysis. The method is applied to EEG data from a psychological experiment, obtaining results which indicate the relevance of this method in the context of cognitive science as well as in other fields.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 069 
Y1  - 2004
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-20106
ER  - 
TY  - JOUR
A1  - Almeida, Leonardo A.
A1  - Sana, H.
A1  - Taylor, W.
A1  - Barbá, Rodolfo
A1  - Bonanos, Alceste Z.
A1  - Crowther, Paul
A1  - Damineli, Augusto
A1  - de Koter, A.
A1  - de Mink, Selma E.
A1  - Evans, C. J.
A1  - Gieles, Mark
A1  - Grin, Nathan J.
A1  - Hénault-Brunet, V.
A1  - Langer, Norbert
A1  - Lennon, D.
A1  - Lockwood, Sean
A1  - Maíz Apellániz, Jesús
A1  - Moffat, A. F. J.
A1  - Neijssel, C.
A1  - Norman, C.
A1  - Ramírez-Agudelo, O. H.
A1  - Richardson, N. D.
A1  - Schootemeijer, Abel
A1  - Shenar, Tomer
A1  - Soszyński, Igor
A1  - Tramper, Frank
A1  - Vink, J. S.
T1  - The tarantula massive binary monitoring
BT  - I. Observational campaign and OB-type spectroscopic binaries
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context:
Massive binaries play a crucial role in the Universe. Knowing the distributions of their orbital parameters is important for a wide range of topics from stellar feedback to binary evolution channels and from the distribution of supernova types to gravitational wave progenitors, yet no direct measurements exist outside the Milky Way.
Aims:
The Tarantula Massive Binary Monitoring project was designed to help fill this gap by obtaining multi-epoch radial velocity (RV) monitoring of 102 massive binaries in the 30 Doradus region.
Methods: 
In this paper we analyze 32 FLAMES/GIRAFFE observations of 93 O- and 7 B-type binaries. We performed a Fourier analysis and obtained orbital solutions for 82 systems: 51 single-lined (SB1) and 31 double-lined (SB2) spectroscopic binaries.
Results: 
Overall, the binary fraction and orbital properties across the 30 Doradus region are found to be similar to existing Galactic samples. This indicates that within these domains environmental effects are of second order in shaping the properties of massive binary systems. A small difference is found in the distribution of orbital periods, which is slightly flatter (in log space) in 30 Doradus than in the Galaxy, although this may be compatible within error estimates and differences in the fitting methodology. Also, orbital periods in 30 Doradus can be as short as 1.1 d, somewhat shorter than seen in Galactic samples. Equal mass binaries (q> 0.95) in 30 Doradus are all found outside NGC 2070, the central association that surrounds R136a, the very young and massive cluster at 30 Doradus’s core. Most of the differences, albeit small, are compatible with expectations from binary evolution. One outstanding exception, however, is the fact that earlier spectral types (O2–O7) tend to have shorter orbital periods than later spectral types (O9.2–O9.7).
Conclusions: 
Our results point to a relative universality of the incidence rate of massive binaries and their orbital properties in the metallicity range from solar (Z⊙) to about half solar. This provides the first direct constraints on massive binary properties in massive star-forming galaxies at the Universe’s peak of star formation at redshifts z ~ 1 to 2 which are estimated to have Z ~ 0.5 Z⊙.
KW  - stars: early-type
KW  - stars: massive
KW  - binaries: spectroscopic
KW  - binaries: close
Y1  - 2017
U6  - https://doi.org/10.1051/0004-6361/201629844
SN  - 1432-0746
VL  - 598
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Alqahtani, Obaid
A1  - Babics, Maxime
A1  - Gorenflot, Julien
A1  - Savikhin, Victoria
A1  - Ferron, Thomas
A1  - Balawi, Ahmed H.
A1  - Paulke, Andreas
A1  - Kan, Zhipeng
A1  - Pope, Michael
A1  - Clulow, Andrew J.
A1  - Wolf, Jannic
A1  - Burn, Paul L.
A1  - Gentle, Ian R.
A1  - Neher, Dieter
A1  - Toney, Michael F.
A1  - Laquai, Frederic
A1  - Beaujuge, Pierre M.
A1  - Collins, Brian A.
T1  - Mixed Domains Enhance Charge Generation and Extraction in Bulk-Heterojunction Solar Cells with Small-Molecule Donors
JF  - Advanced energy materials
N2  - The interplay between nanomorphology and efficiency of polymer-fullerene bulk-heterojunction (BHJ) solar cells has been the subject of intense research, but the generality of these concepts for small-molecule (SM) BHJs remains unclear. Here, the relation between performance; charge generation, recombination, and extraction dynamics; and nanomorphology achievable with two SM donors benzo[1,2-b:4,5-b]dithiophene-pyrido[3,4-b]-pyrazine BDT(PPTh2)(2), namely SM1 and SM2, differing by their side-chains, are examined as a function of solution additive composition. The results show that the additive 1,8-diiodooctane acts as a plasticizer in the blends, increases domain size, and promotes ordering/crystallinity. Surprisingly, the system with high domain purity (SM1) exhibits both poor exciton harvesting and severe charge trapping, alleviated only slightly with increased crystallinity. In contrast, the system consisting of mixed domains and lower crystallinity (SM2) shows both excellent exciton harvesting and low charge recombination losses. Importantly, the onset of large, pure crystallites in the latter (SM2) system reduces efficiency, pointing to possible differences in the ideal morphologies for SM-based BHJ solar cells compared with polymer-fullerene devices. In polymer-based systems, tie chains between pure polymer crystals establish a continuous charge transport network, whereas SM-based active layers may in some cases require mixed domains that enable both aggregation and charge percolation to the electrodes.
KW  - charge transport
KW  - domain purity
KW  - microscopy
KW  - mixed domains
KW  - organic solar cells
KW  - photovoltaic devices
KW  - resonant X-ray scattering
KW  - small molecules
KW  - transient spectroscopy
Y1  - 2018
U6  - https://doi.org/10.1002/aenm.201702941
SN  - 1614-6832
SN  - 1614-6840
VL  - 8
IS  - 19
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Anders, Janet
A1  - Sait, Connor R. J.
A1  - Horsley, Simon A. R.
T1  - Quantum Brownian motion for magnets
JF  - New journal of physics : the open-access journal for physics
N2  - Spin precession in magnetic materials is commonly modelled with the classical phenomenological Landau-Lifshitz-Gilbert (LLG) equation. Based on a quantized three-dimensional spin + environment Hamiltonian, we here derive a spin operator equation of motion that describes precession and includes a general form of damping that consistently accounts for memory, coloured noise and quantum statistics. The LLG equation is recovered as its classical, Ohmic approximation. We further introduce resonant Lorentzian system-reservoir couplings that allow a systematic comparison of dynamics between Ohmic and non-Ohmic regimes. Finally, we simulate the full non-Markovian dynamics of a spin in the semi-classical limit. At low temperatures, our numerical results demonstrate a characteristic reduction and flattening of the steady state spin alignment with an external field, caused by the quantum statistics of the environment. The results provide a powerful framework to explore general three-dimensional dissipation in quantum thermodynamics.
KW  - open quantum systems
KW  - coloured and quantum noise
KW  - memory effects
KW  - spin
KW  - dynamics
KW  - LLG equation
KW  - magnetisation
KW  - quantum thermodynamics
Y1  - 2022
U6  - https://doi.org/10.1088/1367-2630/ac4ef2
SN  - 1367-2630
VL  - 24
IS  - 3
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Andersson, Edvin K. W.
A1  - Sångeland, Christofer
A1  - Berggren, Elin
A1  - Johansson, Fredrik O. L.
A1  - Kühn, Danilo
A1  - Lindblad, Andreas
A1  - Mindemark, Jonas
A1  - Hahlin, Maria
T1  - Early-stage decomposition of solid polymer electrolytes in Li-metal batteries
JF  - Journal of materials chemistry : A, Materials for energy and sustainability
N2  - Development of functional and stable solid polymer electrolytes (SPEs) for battery applications is an important step towards both safer batteries and for the realization of lithium-based or anode-less batteries. The interface between the lithium and the solid polymer electrolyte is one of the bottlenecks, where severe degradation is expected. Here, the stability of three different SPEs - poly(ethylene oxide) (PEO), poly(epsilon-caprolactone) (PCL) and poly(trimethylene carbonate) (PTMC) - together with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt, is investigated after they have been exposed to lithium metal under UHV conditions. Degradation compounds, e.g. Li-O-R, LiF and LixSyOz, are identified for all SPEs using soft X-ray photoelectron spectroscopy. A competing degradation between polymer and salt is identified in the outermost surface region (<7 nm), and is dependent on the polymer host. PTMC:LiTFSI shows the most severe decomposition of both polymer and salt followed by PCL:LiTFSI and PEO:LiTFSI. In addition, the movement of lithium species through the decomposed interface shows large variation depending on the polymer electrolyte system.
Y1  - 2021
U6  - https://doi.org/10.1039/d1ta05015j
SN  - 2050-7488
SN  - 2050-7496
VL  - 9
IS  - 39
SP  - 22462
EP  - 22471
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - GEN
A1  - Angüner, Ekrem Oǧuzhan
A1  - Aharonian, Felix A.
A1  - Bordas, Pol
A1  - Casanova, Sabrina
A1  - Hoischen, Clemens
A1  - Oya, I.
A1  - Ziegler, A.
T1  - HESS J1826-130
BT  - a very hard gamma-Ray spectrum source in the Galactic Plane
T2  - AIP conference proceedings / American Institute of Physics
N2  - HESS J1826-130 is an unidentified hard spectrum source discovered by H.E.S.S. along the Galactic plane, the spectral index being Gamma = 1.6 with an exponential cut-off at about 12 TeV. While the source does not have a clear counterpart at longer wavelengths, the very hard spectrum emission at TeV energies implies that electrons or protons accelerated up to several hundreds of TeV are responsible for the emission. In the hadronic case, the VHE emission can be produced by runaway cosmic-rays colliding with the dense molecular clouds spatially coincident with the H.E.S.S. source.
Y1  - 2017
SN  - 978-0-7354-1456-3
U6  - https://doi.org/10.1063/1.4968928
SN  - 0094-243X
SN  - 1551-7616
VL  - 1792
IS  - 1
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - THES
A1  - Anielski, Alexander
T1  - Entwicklung einer mikrofluidischen, adaptiv geregelten Messapparatur zur quantitativen Untersuchung von Chemotaxis mit Hilfe der Flussfotolyse
KW  - Flussfotolyse
KW  - Konzentration
KW  - Chemotaxis
KW  - Mikrokanal
KW  - Dictyostelium
KW  - flow photolysis
KW  - concentration
KW  - chemotaxis
KW  - microchannel
KW  - Dictyostelium
Y1  - 2015
ER  - 
TY  - JOUR
A1  - Anielski, Alexander
A1  - Barbosa Pfannes, Eva Katharina
A1  - Beta, Carsten
T1  - Adaptive microfluidic gradient generator for quantitative chemotaxis experiments
JF  - Review of scientific instruments : a monthly journal devoted to scientific instruments, apparatus, and techniques
N2  - Chemotactic motion in a chemical gradient is an essential cellular function that controls many processes in the living world. For a better understanding and more detailed modelling of the underlying mechanisms of chemotaxis, quantitative investigations in controlled environments are needed. We developed a setup that allows us to separately address the dependencies of the chemotactic motion on the average background concentration and on the gradient steepness of the chemoattractant. In particular, both the background concentration and the gradient steepness can be kept constant at the position of the cell while it moves along in the gradient direction. This is achieved by generating a well-defined chemoattractant gradient using flow photolysis. In this approach, the chemoattractant is released by a light-induced reaction from a caged precursor in a microfluidic flow chamber upstream of the cell. The flow photolysis approach is combined with an automated real-time cell tracker that determines changes in the cell position and triggers movement of the microscope stage such that the cell motion is compensated and the cell remains at the same position in the gradient profile. The gradient profile can be either determined experimentally using a caged fluorescent dye or may be alternatively determined by numerical solutions of the corresponding physical model. To demonstrate the function of this adaptive microfluidic gradient generator, we compare the chemotactic motion of Dictyostelium discoideum cells in a static gradient and in a gradient that adapts to the position of the moving cell. Published by AIP Publishing.
Y1  - 2017
U6  - https://doi.org/10.1063/1.4978535
SN  - 0034-6748
SN  - 1089-7623
VL  - 88
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - THES
A1  - Antonelli, Andrea
T1  - Accurate waveform models for gravitational-wave astrophysics: synergetic approaches from analytical relativity
N2  - Gravitational-wave (GW) astrophysics is a field in full blossom. Since the landmark detection of GWs from a binary black hole on September 14th 2015, fifty-two compact-object binaries have been reported by the LIGO-Virgo collaboration. Such events carry astrophysical and cosmological information ranging from an understanding of how black holes and neutron stars are formed, what neutron stars are composed of, how the Universe expands, and allow testing general relativity in the highly-dynamical strong-field regime. It is the goal of GW astrophysics to extract such information as accurately as possible. Yet, this is only possible if the tools and technology used to detect and analyze GWs are advanced enough. A key aspect of GW searches are waveform models, which encapsulate our best predictions for the gravitational radiation under a certain set of parameters, and that need to be cross-correlated with data to extract GW signals. Waveforms must be very accurate to avoid missing important physics in the data, which might be the key to answer the fundamental questions of GW astrophysics. The continuous improvements of the current LIGO-Virgo detectors, the development of next-generation ground-based detectors such as the Einstein Telescope or the Cosmic Explorer, as well as the development of the Laser Interferometer Space Antenna (LISA), demand accurate waveform models. While available models are enough to capture the low spins, comparable-mass binaries routinely detected in LIGO-Virgo searches, those for sources from both current and next-generation ground-based and spaceborne detectors must be accurate enough to detect binaries with large spins and asymmetry in the masses. Moreover, the thousands of sources that we expect to detect with future detectors demand accurate waveforms to mitigate biases in the estimation of signals’ parameters due to the presence of a foreground of many sources that overlap in the frequency band. This is recognized as one of the biggest challenges for the analysis of future-detectors’ data, since biases might hinder the extraction of important astrophysical and cosmological information from future detectors’ data. In the first part of this thesis, we discuss how to improve waveform models for binaries with high spins and asymmetry in the masses. In the second, we present the first generic metrics that have been proposed to predict biases in the presence of a foreground of many overlapping signals in GW data.
For the first task, we will focus on several classes of analytical techniques. Current models for LIGO and Virgo studies are based on the post-Newtonian (PN, weak-field, small velocities) approximation that is most natural for the bound orbits that are routinely detected in GW searches. However, two other approximations have risen in prominence, the post-Minkowskian (PM, weak- field only) approximation natural for unbound (scattering) orbits and the small-mass-ratio (SMR) approximation typical of binaries in which the mass of one body is much bigger than the other. These are most appropriate to binaries with high asymmetry in the masses that challenge current waveform models. Moreover, they allow one to “cover” regions of the parameter space of coalescing binaries, thereby improving the interpolation (and faithfulness) of waveform models. The analytical approximations to the relativistic two-body problem can synergically be included within the effective-one-body (EOB) formalism, in which the two-body information from each approximation can be recast into an effective problem of a mass orbiting a deformed Schwarzschild (or Kerr) black hole. The hope is that the resultant models can cover both the low-spin comparable-mass binaries that are routinely detected, and the ones that challenge current models. The first part of this thesis is dedicated to a study about how to best incorporate information from the PN, PM, SMR and EOB approaches in a synergistic way. We also discuss how accurate the resulting waveforms are, as compared against numerical-relativity (NR) simulations. We begin by comparing PM models, whether alone or recast in the EOB framework, against PN models and NR simulations. We will show that PM information has the potential to improve currently-employed models for LIGO and Virgo, especially if recast within the EOB formalism. This is very important, as the PM approximation comes with a host of new computational techniques from particle physics to exploit. Then, we show how a combination of PM and SMR approximations can be employed to access previously-unknown PN orders, deriving the third subleading PN dynamics for spin-orbit and (aligned) spin1-spin2 couplings. Such new results can then be included in the EOB models currently used in GW searches and parameter estimation studies, thereby improving them when the binaries have high spins. Finally, we build an EOB model for quasi-circular nonspinning binaries based on the SMR approximation (rather than the PN one as usually done). We show how this is done in detail without incurring in the divergences that had affected previous attempts, and compare the resultant model against NR simulations. We find that the SMR approximation is an excellent approximation for all (quasi-circular nonspinning) binaries, including both the equal-mass binaries that are routinely detected in GW searches and the ones with highly asymmetric masses. In particular, the SMR-based models compare much better than the PN models, suggesting that SMR-informed EOB models might be the key to model binaries in the future. In the second task of this thesis, we work within the linear-signal ap- proximation and describe generic metrics to predict inference biases on the parameters of a GW source of interest in the presence of confusion noise from unfitted foregrounds and from residuals of other signals that have been incorrectly fitted out. We illustrate the formalism with simple (yet realistic) LISA sources, and demonstrate its validity against Monte-Carlo simulations. The metrics we describe pave the way for more realistic studies to quantify the biases with future ground-based and spaceborne detectors.
N2  - Wenn zwei kompakte Objekte wie Schwarze Löcher oder Neutronensterne kollidieren, wird der Raum und die Zeit um sie herum stark gekrümmt. Der effekt sind Störungen der Raumzeit, sogenannte Gravitationswellen, die sich im gesamten Universum ausbreiten.

Mit den leistungsstarken und präzisen Netzwerken von Detektoren und der Arbeit vieler Wissenschaftler rund um den Globus kann man Gravitationswellen auf der Erde messen.

Gravitationswellen tragen Informationen über das System, das sie erzeugt hat. Insbesondere kann man erfahren, wie sich die kompakten Objekte gebildet haben und woraus sie bestehen. Daraus lässt sich ableiten, wie sich das Universum ausdehnt, und man kann die Allgemeine Relativitätstheorie in Regionen mit starker Gravitation testen.

Um diese Informationen zu extrahieren, werden genaue Modelle benötigt. Modelle können entweder numerisch durch Lösen der berühmten Einstein-Gleichungen oder analytisch durch Annäherung an deren Lösungen gewonnen werden. In meiner Arbeit haben wir den zweiten Ansatz verfolgt, um sehr genaue Vorhersagen für die Signale zu erhalten, die bei kommenden Beobachtungen durch Gravitationswellendetektoren verwendet werden können.
KW  - gravitational waves
KW  - Gravitationswellen
KW  - general relativity
KW  - allgemeine Relativitätstheorie
KW  - data analysis
KW  - Datenanalyse
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-576671
ER  - 
TY  - JOUR
A1  - Aranson, Igor S.
A1  - Pikovskij, Arkadij
T1  - Confinement and collective escape of active particles
JF  - Physical review letters
N2  - Active matter broadly covers the dynamics of self-propelled particles. 
While the onset of collective behavior in homogenous active systems is relatively well understood, the effect of inhomogeneities such as obstacles and traps lacks overall clarity. 
Here, we study how interacting, self-propelled particles become trapped and released from a trap. 
We have found that captured particles aggregate into an orbiting condensate with a crystalline structure. As more particles are added, the trapped condensates escape as a whole. 
Our results shed light on the effects of confinement and quenched disorder in active matter.
Y1  - 2022
U6  - https://doi.org/10.1103/PhysRevLett.128.108001
SN  - 0031-9007
SN  - 1079-7114
SN  - 1092-0145
VL  - 128
IS  - 10
PB  - American Physical Society
CY  - College Park, Md.
ER  - 
TY  - JOUR
A1  - Archambault, S.
A1  - Archer, A.
A1  - Benbow, W.
A1  - Bird, R.
A1  - Bourbeau, E.
A1  - Brantseg, T.
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Byrum, K.
A1  - Cerruti, M.
A1  - Christiansen, J. L.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Daniel, M. K.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fleischhack, H.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Geringer-Sameth, A.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Hütten, M.
A1  - Hakansson, N.
A1  - Hanna, D.
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Hummensky, B.
A1  - Johnson, C. A.
A1  - Kaaret, P.
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Koushiappas, S.
A1  - Krause, M.
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nieto, D.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Pohl, M.
A1  - Popkow, A.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Smith, A. W.
A1  - Staszak, D.
A1  - Telezhinsky, Igor O.
A1  - Trepanier, S.
A1  - Tucci, J. V.
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wilcox, P.
A1  - Williams, D. A.
A1  - Zitzer, B.
T1  - Dark matter constraints from a joint analysis of dwarf Spheroidal galaxy observations with VERITAS
JF  - Physical review : D, Particles, fields, gravitation, and cosmology
N2  - We present constraints on the annihilation cross section of weakly interacting massive particles dark matter based on the joint statistical analysis of four dwarf galaxies with VERITAS. These results are derived from an optimized photon weighting statistical technique that improves on standard imaging atmospheric Cherenkov telescope (IACT) analyses by utilizing the spectral and spatial properties of individual photon events. We report on the results of similar to 230 hours of observations of five dwarf galaxies and the joint statistical analysis of four of the dwarf galaxies. We find no evidence of gamma-ray emission from any individual dwarf nor in the joint analysis. The derived upper limit on the dark matter annihilation cross section from the joint analysis is 1.35 x 10(-23) cm(3) s(-1) at 1 TeV for the bottom quark (b (b) over bar) final state, 2.85 x 10(-24) cm(3) s(-1) at 1 TeV for the tau lepton (tau+tau(-)) final state and 1.32 x 10-25 cm(3) s(-1) at 1 TeV for the gauge boson (gamma gamma) final state.
Y1  - 2017
U6  - https://doi.org/10.1103/PhysRevD.95.082001
SN  - 2470-0010
SN  - 2470-0029
VL  - 95
IS  - 8
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Archambault, S.
A1  - Archer, A.
A1  - Benbow, W.
A1  - Bird, Ralph
A1  - Bourbeau, E.
A1  - Bouvier, A.
A1  - Buchovecky, M.
A1  - Bugaev, V.
A1  - Cardenzana, J. V.
A1  - Cerruti, M.
A1  - Ciupik, L.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Daniel, M. K.
A1  - Errando, M.
A1  - Falcone, A.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fleischhack, H.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Gillanders, G. H.
A1  - Griffin, S.
A1  - Hanna, D.
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Hutten, M.
A1  - Johnson, C. A.
A1  - Kaaret, P.
A1  - Kar, P.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krause, M.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - Maier, G.
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nieto, D.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Pohl, Martin
A1  - Popkow, A.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Staszak, D.
A1  - Telezhinsky, Igor O.
A1  - Trepanier, S.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wilcox, P.
A1  - Williams, D. A.
A1  - Zitzer, B.
T1  - Gamma-ray observations under bright moonlight with VERITAS
JF  - Astroparticle physics
N2  - Imaging atmospheric Cherenkov telescopes (IACTs) are equipped with sensitive photomultiplier tube (PMT) cameras. Exposure to high levels of background illumination degrades the efficiency of and potentially destroys these photo-detectors over time, so IACTs cannot be operated in the same configuration in the presence of bright moonlight as under dark skies. Since September 2012, observations have been carried out with the VERITAS IACTs under bright moonlight (defined as about three times the night-sky-background (NSB) of a dark extragalactic field, typically occurring when Moon illumination > 35%) in two observing modes, firstly by reducing the voltage applied to the PMTs and, secondly, with the addition of ultra-violet (UV) bandpass filters to the cameras. This has allowed observations at up to about 30 times previous NSB levels (around 80% Moon illumination), resulting in 30% more observing time between the two modes over the course of a year. These additional observations have already allowed for the detection of a flare from the 1ES 1727 + 502 and for an observing program targeting a measurement of the cosmic-ray positron fraction. We provide details of these new observing modes and their performance relative to the standard VERITAS observations. (C) 2017 Elsevier B.V. All rights reserved.
KW  - Instrumentation
KW  - Moonlight
KW  - Observing methods
KW  - VERITAS
KW  - IACT
Y1  - 2017
U6  - https://doi.org/10.1016/j.astropartphys.2017.03.001
SN  - 0927-6505
SN  - 1873-2852
VL  - 91
SP  - 34
EP  - 43
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Archambault, S.
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Bourbeau, E.
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Cerruti, M.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Dwarkadas, Vikram V.
A1  - Errando, M.
A1  - Falcone, A.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fleischhack, H.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Griffin, S.
A1  - Huetten, M.
A1  - Hanna, D.
A1  - Holder, J.
A1  - Johnson, C. A.
A1  - Kaaret, P.
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krause, M.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Maier, G.
A1  - McArthur, S.
A1  - McCann, A.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nieto, D.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, Nahee
A1  - Pohl, Martin
A1  - Popkow, A.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Slane, P.
A1  - Staszak, D.
A1  - Telezhinsky, Igor O.
A1  - Trepanier, S.
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Weisgarber, T.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Zitzer, B.
T1  - Gamma-ray Observations of Tycho's Supernova Remnant with VERITAS and Fermi
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
KW  - material
KW  - data behind figure
Y1  - 2017
U6  - https://doi.org/10.3847/1538-4357/836/1/23
SN  - 0004-637X
SN  - 1538-4357
VL  - 836
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Archer, A.
A1  - Benbow, W.
A1  - Bird, R.
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Daniel, M. K.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Gillanders, G.
A1  - Huetten, M.
A1  - Hanna, D.
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, C. A.
A1  - Kaaret, P.
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krause, M.
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - Maier, G.
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Petrashyk, A.
A1  - Pohl, M.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Staszak, D.
A1  - Sushch, I.
A1  - Wakely, S. P.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Williamson, T. J.
A1  - Zitzer, B.
T1  - Measurement of cosmic-ray electrons at TeV energies by VERITAS
JF  - Physical review : D, Particles, fields, gravitation, and cosmology
N2  - Cosmic-ray electrons and positrons (CREs) at GeV-TeV energies are a unique probe of our local Galactic neighborhood. CREs lose energy rapidly via synchrotron radiation and inverse-Compton scattering processes while propagating within the Galaxy, and these losses limit their propagation distance. For electrons with TeV energies, the limit is on the order of a kiloparsec. Within that distance, there are only a few known astrophysical objects capable of accelerating electrons to such high energies. It is also possible that the CREs are the products of the annihilation or decay of heavy dark matter (DM) particles. VERITAS, an array of imaging air Cherenkov telescopes in southern Arizona, is primarily utilized for gamma-ray astronomy but also simultaneously collects CREs during all observations. We describe our methods of identifying CREs in VERITAS data and present an energy spectrum, extending from 300 GeV to 5 TeV, obtained from approximately 300 hours of observations. A single power-law fit is ruled out in VERITAS data. We find that the spectrum of CREs is consistent with a broken power law, with a break energy at 710 +/- 40(stat) +/- 140(syst) GeV.
Y1  - 2018
U6  - https://doi.org/10.1103/PhysRevD.98.062004
SN  - 2470-0010
SN  - 2470-0029
VL  - 98
IS  - 6
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Archer, A.
A1  - Benbow, W.
A1  - Bird, R.
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Bugaev, V.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fleischhack, H.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Hanna, D.
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Hutten, M.
A1  - Johnson, C. A.
A1  - Kaaret, P.
A1  - Kelley-Hoskins, N.
A1  - Kieda, D.
A1  - Krause, M.
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Maier, G.
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nieto, D.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Popkow, A.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I.
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weiner, O. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Wissel, S. A.
A1  - Zitzer, B.
T1  - Measurement of the iron spectrum in cosmic rays by VERITAS
JF  - Physical review : D, Particles, fields, gravitation, and cosmology
N2  - We present a new measurement of the energy spectrum of iron nuclei in cosmic rays from 20 TeV to 500 TeV; The measurement makes use of a template-based analysis method, which, for the first time, is applied to the energy reconstruction of iron-induced air showers recorded by the VERITAS array of imaging atmospheric Cherenkov telescopes. The event selection makes use of the direct Cherenkov light which is emitted by charged particles before the first interaction, as well as other parameters related to the shape of the recorded air shower images. The measured spectrum is well described by a power law dF/dE = f(0) center dot (E/E-0)(-gamma) over the full energy range, with gamma = 2.82 +/- 0.30(stat)(-0.27)(+0.24)(syst) and f(0) = (4.82 +/- 0.98(stat)(-2.70)(+2.12)(syst)) x 10(-7) m(-2) s(-1) TeV-1 sr(-1) at E-0 = 50 TeV, with no indication of a cutoff or spectral break. The measured differential flux is compatible with previous results, with improved statistical uncertainty at the highest energies.
Y1  - 2018
U6  - https://doi.org/10.1103/PhysRevD.98.022009
SN  - 2470-0010
SN  - 2470-0029
VL  - 98
IS  - 2
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Buckley, J. H.
A1  - Chromey, A. J.
A1  - Cui, Wei
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, J. P.
A1  - Fortson, Lucy
A1  - Furniss, Amy
A1  - Gent, A.
A1  - Gueta, O.
A1  - Hanna, David
A1  - Hassan, T.
A1  - Hervet, Olivier
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - McCann, A.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Ong, R. A.
A1  - Otte, Adam Nepomuk
A1  - Pandel, D.
A1  - Park, N.
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Sadeh, I
A1  - Santander, Marcos
A1  - Scott, S. S.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Sushch, Iurii
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Williamson, T. J.
A1  - Zitzer, B.
T1  - A Search for Pulsed Very High-energy Gamma-Rays from 13 Young Pulsars in Archival VERITAS Data
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We conduct a search for periodic emission in the very high-energy (VHE) gamma-ray band (E > 100 GeV) from a total of 13 pulsars in an archival VERITAS data set with a total exposure of over 450 hr. The set of pulsars includes many of the brightest young gamma-ray pulsars visible in the Northern Hemisphere. The data analysis resulted in nondetections of pulsed VHE gamma-rays from each pulsar. Upper limits on a potential VHE gamma-ray flux are derived at the 95% confidence level above three energy thresholds using two methods. These are the first such searches for pulsed VHE emission from each of the pulsars, and the obtained limits constrain a possible flux component manifesting at VHEs as is seen for the Crab pulsar.
KW  - gamma rays: general
KW  - pulsars: general
KW  - stars: neutron
Y1  - 2019
U6  - https://doi.org/10.3847/1538-4357/ab14f4
SN  - 0004-637X
SN  - 1538-4357
VL  - 876
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Bugaev, V
A1  - Cui, Wei
A1  - Danie, M. K.
A1  - Falcone, A.
A1  - Feng, Qi
A1  - Finley, John P.
A1  - Flinders, A.
A1  - Fortson, L.
A1  - Furniss, Amy
A1  - Gillanders, Gerard H.
A1  - Huttens, M.
A1  - Hanna, David
A1  - Hervet, O.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, Philip
A1  - Kar, P.
A1  - Kelley-Hoskins, N.
A1  - Kieda, David
A1  - Krause, Maria
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Lin, T. T. Y.
A1  - McArthur, S.
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Nieto, Daniel
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Park, Nahee
A1  - Petrashyk, A.
A1  - Pohl, Martin
A1  - Popkow, Alexis
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynold, P. T.
A1  - Richards, Gregory T.
A1  - Roache, E.
A1  - Rulten, C.
A1  - Sadeh, I
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Tyler, J.
A1  - Wakely, S. P.
A1  - Weiner, O. M.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, P.
A1  - Wilhelm, Alina
A1  - Williams, David A.
A1  - Brisken, W. F.
A1  - Pontrelli, P.
T1  - HESS J1943+213
BT  - An extreme blazar shining through the galactic plane
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - HESS J1943+213 is a very high energy (VHE; > 100 GeV) gamma-ray source in the direction of the Galactic plane. Studies exploring the classification of the source are converging toward its identification as an extreme synchrotron BL Lac object. Here we present 38 hr of VERITAS observations of HESS J1943+213 taken over 2 yr. The source is detected with a significance of similar to 20 standard deviations, showing a remarkably stable flux and spectrum in VHE gamma-rays. Multifrequency Very Long Baseline Array (VLBA) observations of the source confirm the extended, jet-like structure previously found in the 1.6 GHz band with the European VLBI Network and detect this component in the 4.6 and 7.3 GHz bands. The radio spectral indices of the core and the jet and the level of polarization derived from the VLBA observations are in a range typical for blazars. Data from VERITAS, Fermi-LAT, Swift-XRT, the FLWO 48 ' telescope, and archival infrared and hard X-ray observations are used to construct and model the spectral energy distribution (SED) of the source with a synchrotron self-Compton model. The well-measured gamma-ray peak of the SED with VERITAS and Fermi-LAT provides constraining upper limits on the source redshift. Possible contribution of secondary gamma-rays from ultra-high-energy cosmic-ray-initiated electromagnetic cascades to the gamma-ray emission is explored, finding that only a segment of the VHE spectrum can be accommodated with this process. A variability search is performed across X-ray and gamma-ray bands. No statistically significant flux or spectral variability is detected.
KW  - astroparticle physics
KW  - BL Lacertae objects: individual (HESS J1943+213, VER J1943+213)
KW  - galaxies: active
KW  - galaxies: jets
KW  - galaxies: nuclei
KW  - gamma rays: galaxies
Y1  - 2018
U6  - https://doi.org/10.3847/1538-4357/aacbd0
SN  - 0004-637X
SN  - 1538-4357
VL  - 862
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - THES
A1  - Aretz, Sarah
T1  - Entwicklung und Evaluation eines Testinstruments zur Untersuchung von Vorkenntnissen und Präkonzepten in der Kosmologie
T1  - Development and evaluation of a test instrument to investigate students’ prior knowledge and conceptions in cosmology
N2  - Kosmologie beschreibt die Entwicklung des Universums als Ganzes. Kosmologische Entdeckungen in Theorie und Praxis haben daher unser modernes wissenschaftliches Weltbild entscheidend ge­prägt. Die Vermittlung eines modernen Weltbildes durch Unterricht ist ein häufiger Wunsch in der naturwissenschaftlichen Bildungsdiskussion. Dennoch exis­tieren weiterhin Forschungs- und Entwicklungsbedarfe. Kosmologische Themen finden sich häufig in den Medien und sind gleichzeitig weiter vom Alltag entfernt, so dass sich hier besonders leicht wissenschaftlich inkorrekte Vorstellungen entwickeln können, die zu Problemen im Unterricht führen können.

Das Ziel dieser wissenschaftlichen Arbeit ist es, zu diesem Forschungsgebiet beizutragen und die Voraussetzungen hinsichtlich vorhandener Vorkenntnisse und Präkonzepte in Kosmologie, mit denen Schülerinnen und Schüler in den Unterricht kommen, zu untersuchen und anschließend mit denen anderer Länder zu vergleichen. Dies erfolgt anhand einer qualitativen Inhaltsanalyse eines offenen Fragebogens. Auf dieser Grundlage wird schließlich ein Multiple-Choice Frage­bogen entwickelt, angewendet und evaluiert.

Die Ergebnisse zeigen große Wissenslücken im Bereich der Kosmologie auf und geben erste Hin­weise auf vorhandene Unterschiede zwischen den Ländern. Es existieren ebenfalls einige teils weit verbreitete wissenschaftlich inkorrekte Vorstellungen wie beispiels­weise die Assoziation des Urknalls mit einer Explosion, der Urknall verursacht durch eine Kollision von Teilchen oder größeren Objekten, oder die Vorstellung der Ausdehnung des Universums als neue Entdeckungen und/oder Wissen. Des Weiteren gab nur etwa jeder Fünfte das korrekte Alter des Universums oder die Ausdehnung des Universums als einen der drei Belege der Urknalltheorie an, während fast 40% keinen einzigen Beleg nennen konn­ten. Für den geschlossenen Fragebogen konnten gute Hinweise für verschiedene Validitätsa­spekte herausgearbeitet werden und es existieren erste Hinweise darauf, dass der Fragebogen Wissenszu­wachs messen kann und damit wahrscheinlich zur Unter­suchung der Wirksamkeit von Lerneinhei­ten eingesetzt werden kann. Auch ein entsprechendes Modell zur Verständnisentwicklung der Aus­dehnung des Universums zeigte sich vielversprechend.

Diese Arbeit liefert insgesamt einen Forschungsbeitrag zum Schülervorwissen und Vorstellungen in der Kosmologie und deren Large Scale Assessment. Dies eröffnet die Möglichkeit zukünftiger For­schungen im Bereich von Gruppenvergleichen insbesondere hinsichtlich objektiver Länderverglei­che sowie der Untersuchungen der Wirksamkeit von einzelnen Ler­neinheiten als auch Vergleiche verschiedener Lerneinheiten untereinander.
N2  - Cosmology deals with the development of the universe as a whole. Cosmological discoveries in theory and observation have therefore formed our modern scientific worldview. Transferring a modern worldview through science teaching is a frequent request in science literacy discussion. Nevertheless, there is still a need for research and education development. Cosmological topics often appear in the media and, at the same time, are further away from everyday life. Thus, scientifically incorrect conceptions can develop particularly easy and can lead to problems in class.

The objective of this scientific work is to contribute to this area of research and to investigate the preconditions regarding present knowledge and conceptions in cosmology, which students bring into the classroom, and to compare these with those from other countries. This is done by a qualitative analysis of an open-ended questionnaire. On this basis a multiple-choice questionnaire is developed, applied and evaluated.

The results show large gaps in knowledge in the area of cosmology and provide first indications of differences between countries. There also exist some partially widespread scientifically incorrect conceptions such as the association of the Big Bang with an explosion, the Big Bang being caused by a collision of particles or bigger objects, or the idea of the expansion of the universe meaning new discoveries and/ or knowledge. Furthermore, only every fifth student mentioned the correct age of the universe or the expansion of the universe as one of the three pillars of the Big Bang theory, whereas almost 40% could not name a single evidence. For the closed questionnaire good evidence could be established for different aspects of validity. In addition, there exist first indications, that the questionnaire can measure knowledge gain and therefore can likely be used to investigate the effectiveness of learning units. Moreover, a corresponding model of the development of understanding of the expansion of the universe looked promising.

This study provides research contributions to students' prior knowledge and preconceptions in cosmology and their large-scale assessment. This opens up the possibility of future research in the area of group comparisons in particular concerning objective country comparisons and investigations of the effectiveness of single learning units as well as comparisons of different learning units among each other.
KW  - Präkonzepte
KW  - Schülervorstellungen
KW  - Kosmologie
KW  - Testentwicklung
KW  - Verständnisentwicklungsmodell
KW  - preconceptions
KW  - students' conceptions
KW  - cosmology
KW  - development of test instrument
KW  - construct map
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-425421
ER  - 
TY  - JOUR
A1  - Armin, Ardalan
A1  - Chen, Zhiming
A1  - Jin, Yaocheng
A1  - Zhang, Kai
A1  - Huang, Fei
A1  - Shoaee, Safa
T1  - A Shockley-Type polymer
BT  - Fullerene solar cell
JF  - Advanced energy materials
N2  - Charge extraction rate in solar cells made of blends of electron donating/accepting organic semiconductors is typically slow due to their low charge carrier mobility. This sets a limit on the active layer thickness and has hindered the industrialization of organic solar cells (OSCs). Herein, charge transport and recombination properties of an efficient polymer (NT812):fullerene blend are investigated. This system delivers power conversion efficiency of >9% even when the junction thickness is as large as 800 nm. Experimental results indicate that this material system exhibits exceptionally low bimolecular recombination constant, 800 times smaller than the diffusion-controlled electron and hole encounter rate. Comparing theoretical results based on a recently introduced modified Shockley model for fill factor, and experiments, clarifies that charge collection is nearly ideal in these solar cells even when the thickness is several hundreds of nanometer. This is the first realization of high-efficiency Shockley-type organic solar cells with junction thicknesses suitable for scaling up.
KW  - charge transport
KW  - non-Langevin recombination
KW  - organic solar cells
KW  - thick junctions
Y1  - 2018
U6  - https://doi.org/10.1002/aenm.201701450
SN  - 1614-6832
SN  - 1614-6840
VL  - 8
IS  - 7
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - THES
A1  - Arora, Ashima
T1  - Optical and electric field control of magnetism
T1  - Optische und elektrische Feld Kontrolle des Magnetismus
N2  - Future magnetic recording industry needs a high-density data storage technology. However, switching the magnetization of small bits requires high magnetic fields that cause excessive heat dissipation. Therefore, controlling magnetism without applying external magnetic field is an important research topic for potential applications in data storage devices with low power consumption. Among the different approaches being investigated, two of them stand out, namely i) all-optical helicity dependent switching (AO-HDS) and ii) ferroelectric control of magnetism. This thesis aims to contribute towards a better understanding of the physical processes behinds these effects as well as reporting new and exciting possibility for the optical and/or electric control of magnetic properties. Hence, the thesis contains two differentiated chapters of results; the first devoted to AO-HDS on TbFe alloys and the second to the electric field control of magnetism in an archetypal Fe/BaTiO3 system.
In the first part, the scalability of the AO-HDS to small laser spot-sizes of few microns in the ferrimagnetic TbFe alloy is investigated by spatially resolving the magnetic contrast with photo-emission electron microscopy (PEEM) and X-ray magnetic circular dichroism (XMCD). The results show that the AO-HDS is a local effect within the laser spot size that occurs in the ring-shaped region in the vicinity of thermal demagnetization. Within the ring region, the helicity dependent switching occurs via thermally activated domain wall motion. Further, the thesis reports on a novel effect of thickness dependent inversion of the switching orientation. It addresses some of the important questions like the role of laser heating and the microscopic mechanism driving AO-HDS.

The second part of the thesis focuses on the electric field control of magnetism in an artificial multiferroic heterostructure. The sample consists of an Fe wedge with thickness varying between 0:5 nm and 3 nm, deposited on top of a ferroelectric and ferroelastic BaTiO3 [001]-oriented single crystal substrate. Here, the magnetic contrast is imaged via PEEM and XMCD as a function of out-of-plane voltage. The results show the evidence of the electric field control of superparamagnetism mediated by a ferroelastic modification of the magnetic anisotropy. The changes in the magnetoelastic anisotropy drive the transition from the superparamagnetic to superferromagnetic state at localized sample positions.
N2  - Die Herstellung zukünftiger magnetischer Datenspeicher erfordert eine hohe Speicherdichte mit entsprechend kleinen Bits. Das Schalten der Magnetisierung kleiner Strukturen benötigt jedoch starke Magnetfelder, die einen hohen Energieverbrauch und Wärmeeintrag verursachen. Daher ist das Schalten von Magnetismus ohne Anlegen eines externen Magnetfeldes ein wichtiges Forschungsthema für potentielle Anwendungen in der Datenspeicherung mit geringem Stromverbrauch. Unter den verschiedenen Ansätzen, die verfolgt werden, heben sich zwei hervor, nämlich i) rein optisches helizitätsabhängiges Schalten (AO-HDS) und ii) magnetoelektrische Kontrolle von Magnetismus. Diese Arbeit soll zu einem besseren Verständnis der physikalischen Prozesse beitragen, die hinter diesen Effekten stehen, sowie neue und aufregende Möglichkeiten für die optische und/ oder elektrische Kontrolle magnetischer Eigenschaften aufzeigen. Daher sind die Ergebnisse dieser Arbeit in zwei Kapitel gegliedert; das erste befasst sich mit dem helizitätsabhängigen optischen Schalten in Eisen-Terbium Legierungen und das zweite Kapitel widmet sich der magnetoelektrischen Kopplung in Hybridsystemen, bestehend aus einer ferromagnetischen Eisenschicht welche auf ferroelektrischen Bariumtitanat gewachsen wurde.
Im ersten Kapitel wird die Skalierbarkeit des helizitätsabhängigen optischen Schaltens in ferrimagnetischen Eisen-Terbium Legierungen mit Laserspotgrößen im Mikrometer Bereich untersucht. Photoelektronenmikroskopie (PEEM) in Kombination mit magnetischem Röntgendichroismus (XMCD) wird verwendet um die resultierende Magnetisierung hochaufgelöst abzubilden. Die Ergebnisse zeigen, dass helizitätsabhängiges optisches Schalten ein lokaler Effekt innerhalb des Laserspots ist, der in der ringförmigen Region in der Nähe der thermischen Entmagnetisierung auftritt. Innerhalb der Ringregion erfolgt die Umkehr der Magnetisierung über thermisch aktivierte Domänenwandbewegung. Des Weiteren berichtet die Arbeit über einen neuartigen Effekt der die Helizitätsabhängigkeit mit zunehmender Schichtdicke umkehrt. Auch werden wichtigen Fragen wie der Rolle thermischer Effekt oder die mikroskopische Ursache helizitätsabhängigen Schaltens beleuchtet.
Der zweite Teil der Arbeit konzentriert sich auf die elektrische Kontrolle des Magnetismus in einer künstlichen multiferroischen Heterostruktur. Die Probe besteht aus einem Eisen-Keil mit einer Dicke zwischen 0:5 nm und 3 nm, der auf einem ferroelektrischen und ferroelastischen Bariumtitanat abgeschieden ist. Hier wird der magnetische Kontrast als Funktion des elektrischen Feldes untersucht. Die Ergebnisse belegen die Möglichkeit superparamagnetische Bereiche per elektrischen Feld zu steuern. Die magnetelektrische Kopplung erfolgt durch eine ferroelastische Modifikation der magnetischen Anisotropie. Die Änderungen in der magnetoelastischen Anisotropie erlauben elektrisches Schalten zwischen dem superparamagnetischen zu dem superferromagnetischen Zustand.
KW  - magnetism
KW  - X-ray magnetic circular dichroism (XMCD)
KW  - all-optical helicity dependent switching
KW  - multiferroic heterostructure
KW  - photo-emission electron microscopy (PEEM)
KW  - magnetischem Röntgendichroismus (XMCD)
KW  - Photoelektronenmikroskopie (PEEM)
KW  - Magnetismus
KW  - multiferroischen Heterostruktur
KW  - rein optisches helizitätsabhängiges Schalten (AO-HDS)
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-421479
ER  - 
TY  - JOUR
A1  - Arya, Pooja
A1  - Jelken, Joachim
A1  - Feldmann, David
A1  - Lomadze, Nino
A1  - Santer, Svetlana
T1  - Light driven diffusioosmotic repulsion and attraction of colloidal particles
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - In this paper, we introduce the phenomenon of light driven diffusioosmotic long-range attraction and repulsion of porous particles under irradiation with UV light. The change in the inter-particle interaction potential is governed by flow patterns generated around single colloids and results in reversible aggregation or separation of the mesoporous silica particles that are trapped at a solid surface. The range of the interaction potential extends to several times the diameter of the particle and can be adjusted by varying the light intensity. The "fuel" of the process is a photosensitive surfactant undergoing photo-isomerization from a more hydrophobic trans-state to a rather hydrophilic cis-state. The surfactant has different adsorption affinities to the particles depending on the isomerization state. The trans-isomer, for example, tends to accumulate in the negatively charged pores of the particles, while the cis-isomer prefers to remain in the solution. This implies that when under UV irradiation cis-isomers are being formed within the pores, they tend to diffuse out readily and generate an excess concentration near the colloid's outer surface, ultimately resulting in the initiation of diffusioosmotic flow. The direction of the flow depends strongly on the dynamic redistribution of the fraction of trans- and cis-isomers near the colloids due to different kinetics of photo-isomerization within the pores as compared to the bulk. The unique feature of the mechanism discussed in the paper is that the long-range mutual repulsion but also the attraction can be tuned by convenient external optical stimuli such as intensity so that a broad variety of experimental situations for manipulation of a particle ensemble can be realized.
Y1  - 2020
U6  - https://doi.org/10.1063/5.0007556
SN  - 0021-9606
SN  - 1089-7690
VL  - 152
IS  - 19
PB  - American Institute of Physics
CY  - Melville, NY
ER  - 
TY  - JOUR
A1  - Arya, Pooja
A1  - Jelken, Joachim
A1  - Lomadze, Nino
A1  - Santer, Svetlana
A1  - Bekir, Marek
T1  - Kinetics of photo-isomerization of azobenzene containing surfactants
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry
N2  - We report on photoisomerization kinetics of azobenzene containing surfactants in aqueous solution. The surfactant molecule consists of a positively charged trimethylammonium bromide head group, a hydrophobic spacer connecting via 6 to 10 CH2 groups to the azobenzene unit, and the hydrophobic tail of 1 and 3CH(2) groups. Under exposure to light, the azobenzene photoisomerizes from more stable trans- to metastable cis-state, which can be switched back either thermally in dark or by illumination with light of a longer wavelength. The surfactant isomerization is described by a kinetic model of a pseudo first order reaction approaching equilibrium, where the intensity controls the rate of isomerization until the equilibrated state. The rate constants of the trans-cis and cis-trans photoisomerization are calculated as a function of several parameters such as wavelength and intensity of light, the surfactant concentration, and the length of the hydrophobic tail. The thermal relaxation rate from cis- to trans-state is studied as well. The surfactant isomerization shows a different kinetic below and above the critical micellar concentration of the trans isomer due to steric hindrance within the densely packed micelle but does not depend on the spacer length.
KW  - genomic DNA conformation
KW  - water-interface
KW  - light photocontrol
KW  - driven
KW  - manipulation
KW  - photoisomerization
KW  - molecules
Y1  - 2020
U6  - https://doi.org/10.1063/1.5135913
SN  - 0021-9606
SN  - 1089-7690
VL  - 152
IS  - 2
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - THES
A1  - Aseev, Nikita
T1  - Modeling and understanding dynamics of charged particles in the Earth's inner magnetosphere
T1  - Modellierung und Untersuchung der Dynamik geladener Teilchen in der inneren Magnetosphäre der Erde
N2  - The Earth's inner magnetosphere is a very dynamic system, mostly driven by the external solar wind forcing exerted upon the magnetic field of our planet. Disturbances in the solar wind, such as coronal mass ejections and co-rotating interaction regions, cause geomagnetic storms, which lead to prominent changes in charged particle populations of the inner magnetosphere - the plasmasphere, ring current, and radiation belts. Satellites operating in the regions of elevated energetic and relativistic electron fluxes can be damaged by deep dielectric or surface charging during severe space weather events. Predicting the dynamics of the charged particles and mitigating their effects on the infrastructure is of particular importance, due to our increasing reliance on space technologies.

The dynamics of particles in the plasmasphere, ring current, and radiation belts are strongly coupled by means of collisions and collisionless interactions with electromagnetic fields induced by the motion of charged particles. Multidimensional numerical models simplify the treatment of transport, acceleration, and loss processes of these particles, and allow us to predict how the near-Earth space environment responds to solar storms. The models inevitably rely on a number of simplifications and assumptions that affect model accuracy and complicate the interpretation of the results. In this dissertation, we quantify the processes that control electron dynamics in the inner magnetosphere, paying particular attention to the uncertainties of the employed numerical codes and tools.

We use a set of convenient analytical solutions for advection and diffusion equations to test the accuracy and stability of the four-dimensional Versatile Electron Radiation Belt (VERB-4D) code. We show that numerical schemes implemented in the code converge to the analytical solutions and that the VERB-4D code demonstrates stable behavior independent of the assumed time step. The order of the numerical scheme for the convection equation is demonstrated to affect results of ring current and radiation belt simulations, and it is crucially important to use high-order numerical schemes to decrease numerical errors in the model.

Using the thoroughly tested VERB-4D code, we model the dynamics of the ring current electrons during the 17 March 2013 storm. The discrepancies between the model and observations above 4.5 Earth's radii can be explained by uncertainties in the outer boundary conditions. Simulation results indicate that the electrons were transported from the geostationary orbit towards the Earth by the global-scale electric and magnetic fields.
We investigate how simulation results depend on the input models and parameters. The model is shown to be particularly sensitive to the global electric field and electron lifetimes below 4.5 Earth's radii. The effects of radial diffusion and subauroral polarization streams are also quantified.

We developed a data-assimilative code that blends together a convection model of energetic electron transport and loss and Van Allen Probes satellite data by means of the Kalman filter. We show that the Kalman filter can correct model uncertainties in the convection electric field, electron lifetimes, and boundary conditions. It is also demonstrated how the innovation vector - the difference between observations and model prediction - can be used to identify physical processes missing in the model of energetic electron dynamics.

We computed radial profiles of phase space density of ultrarelativistic electrons, using Van Allen Probes measurements. We analyze the shape of the profiles during geomagnetically quiet and disturbed times and show that the formation of new local minimums in the radial profiles coincides with the ground observations of electromagnetic ion-cyclotron (EMIC) waves. This correlation indicates that EMIC waves are responsible for the loss of ultrarelativistic electrons from the heart of the outer radiation belt into the Earth's atmosphere.
N2  - Die innere Magnetosphäre der Erde ist ein sehr dynamisches System, das hauptsächlich vom äußeren Sonnenwind beeinflusst wird, der auf das Magnetfeld unseres Planeten einwirkt. Störungen im Sonnenwind, wie z.B. koronale Massenauswürfe und sogenannte Korotierende Wechselwirkungsbereiche, verursachen geomagnetische Stürme, die zu deutlichen Veränderungen der Populationen geladener Teilchen in der inneren Magnetosphäre führen - Plasmasphäre, Ringstrom und Strahlungsgürtel. Satelliten, die in Regionen mit erhöhten energetischen und relativistischen Elektronenflüssen betrieben werden, können durch tiefe dielektrische Ladung oder Oberflächenladungen bei schweren Weltraumwetterereignissen beschädigt werden. Die Vorhersage der Dynamik der geladenen Teilchen und die Abschwächung ihrer Auswirkungen auf die Infrastruktur sind heutzutage von besonderer Bedeutung, insbesondere aufgrund unserer zunehmenden Abhängigkeit von Weltraumtechnologien.

Die Dynamik von Teilchen in der Plasmasphäre, des Ringstrom und in den Strahlungsgürteln sind durch Kollisionen und kollisionsfreie Wechselwirkungen mit elektromagnetischen Feldern, die durch die Bewegung geladener Teilchen induziert werden, stark gekoppelt. Mehrdimensionale numerische Modelle vereinfachen die Betrachtung von Transport-, Beschleunigungs- und Verlustprozessen dieser Partikel und ermöglichen es uns, vorherzusagen, wie die erdnahe Weltraumumgebung auf Sonnenstürme reagiert. Die Modelle beruhen zwangsläufig auf einer Reihe von Vereinfachungen und Voraussetzungen, die sich auf die Modellgenauigkeit auswirken und die Interpretation der Ergebnisse erschweren. In dieser Dissertation quantifizieren wir die Prozesse, die die Dynamik der Elektronen in der inneren Magnetosphäre steuern. Dabei richten wir den Fokus insbesondere auch auf die Unsicherheiten der verwendeten numerischen Codes.

Wir verwenden eine Reihe praktischer analytischer Lösungen für Advektions- und Diffusionsgleichungen, um die Genauigkeit und Stabilität des 4-dimensionalen ''Versatile Electron Radiation Belt'' Codes (VERB-4D Code) zu testen. Wir zeigen, dass die im Code implementierten numerischen Schemata zu den analytischen Lösungen konvergieren und der Code sich unabhängig vom angenommenen Zeitschritt stabil verhält. Wir demonstrieren, wie die Genauigkeit des numerischen Schemas für die Konvektionsgleichung die Ergebnisse von Ringstrom- und Strahlungsgürtelsimulationen beeinflussen kann, und dass es von entscheidender Beteutung ist, numerische Schemata höherer Ordnung zu verwenden, um numerische Fehler im Modell zu reduzieren.

Mit dem ausführlich getesteten VERB-4D Code modellieren wir die Dynamik der Ringstromelektronen während des Sturms vom 17. März 2013. Wir zeigen, dass die Diskrepanzen zwischen dem Modell und Beobachtungen oberhalb von 4.5 Erdradien durch Unsicherheiten in den äußeren Randbedingungen erklärt werden können und dass die Elektronen durch die globalen elektrischen und magnetischen Felder von der geostationäre Umlaufbahn zur Erde transportiert wurden.
Wir untersuchen weiterhin, wie die Simulationsergebnisse von den Eingabemodellen und Parametern abhängen. Wir zeigen, dass das Modell besonders empfindlich für das globale elektrische Feld und die Lebensdauer der Elektronen unterhalb von 4.5 Erdradien ist. Außerdem quantifizieren wir auch die Auswirkungen von radialer Diffusion und subauroralen Polarisationsströmen.

Wir haben einen datenassimilativen Code entwickelt, der mithilfe des Kalman-Filters ein Konvektionsmodell für den Transport und den Verlust energetischer Elektronen mit den Satellitendaten der Van Allen Probes kombiniert. Wir zeigen, dass die Verwendung eines Kalman-Filters Modellunsicherheiten im elektrischen Konvektionsfeld, in der Lebensdauer der Elektronen und in den Randbedingungen korrigieren kann. Weiterhin zeigen wir, wie der Innovationsvektor - die Differenz zwischen Beobachtungen und Modellvorhersagen - verwendet werden kann, um physikalische Prozesse zu identifizieren, die im Modell der Dynamik der energetischen Elektronen fehlen.

Außerdem berechnen wir radiale Profile der Phasenraumdichte ultrarelativistischer Elektronen mithilfe von Van Allen Probes-Messungen. Wir analysieren die Form der Profile und zeigen, dass die Entstehung neuer lokaler Minima in den radialen Profilen mit den Bodenbeobachtungen von EMIC-Wellen übereinstimmt. Diese Korrelation legt nahe, dass EMIC-Wellen für den Verlust ultrarelativistischer Elektronen vom Herzen des äußeren Strahlungsgürtels in die Erdatmosphäre verantwortlich sind.
KW  - ring current electrons
KW  - radiation belts
KW  - mathematical modeling
KW  - wave-particle interactions
KW  - data assimilation
KW  - Ringstromelektronen
KW  - Strahlungsgürtel
KW  - mathematische Modellierung
KW  - Wellen-Teilchen Wechselwirkungen
KW  - Datenassimilation
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-479211
ER  - 
TY  - JOUR
A1  - Assagra, Yuri A.O.
A1  - Altafim, Ruy Alberto Pisani
A1  - do Carmo, Joao P.
A1  - Altafim, Ruy A.C.
A1  - Rychkov, Dmitry
A1  - Wirges, Werner
A1  - Gerhard, Reimund
T1  - A new route to piezo-polymer transducers: 3D printing of polypropylene ferroelectrets
JF  - IEEE transactions on dielectrics and electrical insulation
N2  - Here, a promising approach for producing piezo-polymer transducers in a one-step process is presented. Using 3D-printing technology and polypropylene (PP) filaments, we are able to print a two-layered film structure with regular cavities of precisely controlled size and shape. It is found that the 3D-printed samples exhibit piezoelectric coefficients up to 200 pC/N, similar to those of other PP ferroelectrets, and their temporal and thermal behavior is in good agreement with those known of PP ferroelectrets. The piezoelectric response strongly decreases for applied pressures above 20 kPa, as the pressure in the air-filled cavities strongly influences the overall elastic modulus of ferroelectrets.
KW  - 3D printing
KW  - polymer ferroelectrets
KW  - sensors and actuators
KW  - piezoelectrets
KW  - electret polymers
KW  - soft electro-active materials
KW  - functional materials
KW  - soft matter
Y1  - 2020
U6  - https://doi.org/10.1109/TDEI.2020.008461
SN  - 1070-9878
SN  - 1558-4135
VL  - 27
IS  - 5
SP  - 1668
EP  - 1674
PB  - Inst. of Electr. and Electronics Engineers
CY  - Piscataway
ER  - 
TY  - JOUR
A1  - Assmann, Birte
A1  - Thiel, Marco
A1  - Romano, Maria Carmen
A1  - Niemitz, Carsten
T1  - Recurrence plot analyses suggest a novel reference system involved in newborn spontaneous movements
JF  - Behavior research methods : a journal of the Psychonomic Society
N2  - The movements of newborns have been thoroughly studied in terms of reflexes, muscle synergies, leg coordination, and target-directed arm/hand movements. Since these approaches have concentrated mainly on separate accomplishments, there has remained a clear need for more integrated investigations. Here, we report an inquiry in which we explicitly concentrated on taking such a perspective and, additionally, were guided by the methodological concept of home base behavior, which Ilan Golard developed for studies of exploratory behavior in animals. Methods from nonlinear dynamics, such as symbolic dynamics and recurrence plot analyses of kinematic data received from audiovisual newborn recordings, yielded new insights into the spatial and temporal organization of limb movements. In the framework of home base behavior, our approach uncovered a novel reference system of spontaneous newborn movements.
Y1  - 2006
U6  - https://doi.org/10.3758/BF03192793
SN  - 1554-351X
SN  - 1554-3528
VL  - 38
IS  - 3
SP  - 400
EP  - 406
PB  - Springer
CY  - New York
ER  - 
TY  - THES
A1  - Ata, Metin
T1  - Phase-space reconstructions of cosmic velocities and the cosmic web
T1  - Phasenraumrekonstruktionen kosmischer Geschwindigkeiten und des kosmischen Netzes
BT  - structure formation models - galaxy bias models - galaxy redshift surveys - inference analysis
N2  - In the current paradigm of cosmology, the formation of large-scale structures is mainly driven by non-radiating dark matter, making up the dominant part of the matter budget of the Universe. Cosmological observations however, rely on the detection of luminous galaxies, which are biased tracers of the underlying dark matter. In this thesis I present cosmological reconstructions of both, the dark matter density field that forms the cosmic web, and cosmic velocities, for which both aspects of my work are delved into, the theoretical formalism and the results of its applications to cosmological simulations and also to a galaxy redshift survey.The foundation of our method is relying on a statistical approach, in which a given galaxy catalogue is interpreted as a biased realization of the underlying dark matter density field. The inference is computationally performed on a mesh grid by sampling from a probability density function, which describes the joint posterior distribution of matter density and the three dimensional velocity field. The statistical background of our method is described in Chapter ”Implementation of argo”, where the introduction in sampling methods is given, paying special attention to Markov Chain Monte-Carlo techniques. In Chapter ”Phase-Space Reconstructions with N-body  Simulations”, I introduce and implement a novel biasing scheme to relate the galaxy number density to the underlying dark matter, which I decompose into a deterministic part, described by a non-linear and scale-dependent analytic expression, and a stochastic part, by presenting a negative binomial (NB) likelihood function that models deviations from Poissonity. Both bias components had already been studied theoretically, but were so far never tested in a reconstruction algorithm. I test these new contributions againstN-body simulations to quantify improvements and show that, compared to state-of-the-art methods, the stochastic bias is inevitable at wave numbers of k≥0.15h Mpc^−1 in the power spectrum in order to obtain unbiased results from the reconstructions. In the second part of Chapter ”Phase-Space Reconstructions with N-body Simulations” I describe and validate our approach to infer the three dimensional cosmic velocity field jointly with the dark matter density. I use linear perturbation theory for the large-scale bulk flows and a dispersion term to model virialized galaxy motions, showing that our method is accurately recovering the real-space positions of the redshift-space distorted galaxies. I analyze the results with the isotropic and also the two-dimensional power spectrum.Finally, in Chapter ”Phase-space Reconstructions with Galaxy Redshift Surveys”, I show how I combine all findings and results and apply the method to the CMASS (for Constant (stellar) Mass) galaxy catalogue of the Baryon Oscillation Spectroscopic Survey (BOSS). I describe how our method is  accounting  for the observational selection effects inside our reconstruction algorithm. Also, I demonstrate that the renormalization of the prior distribution function is mandatory to account for higher order contributions in the structure formation model, and finally a redshift-dependent bias factor is theoretically motivated and implemented into our method. The various refinements yield unbiased results of the dark matter until scales of k≤0.2 h Mpc^−1in the power spectrum and isotropize the galaxy catalogue down to distances of r∼20h^−1 Mpc in the correlation function. We further test the  results of our cosmic velocity field reconstruction by comparing them to a synthetic mock galaxy catalogue, finding a strong correlation between the mock and the reconstructed  velocities. The applications of both, the density field without redshift-space distortions, and the velocity reconstructions, are very broad and can be used for improved analyses of the baryonic acoustic oscillations, environmental studies of the cosmic web, the kinematic Sunyaev-Zel’dovic or integrated Sachs-Wolfe effect.
N2  - In der gegenwärtigen Anschauung der Kosmologie wird die Bildung von großräumigen Strukturen vor allem durch nicht strahlende, Dunkle Materie beeinflusst, die den überwiegenden Teil des Materieanteils des Universums ausmacht. Kosmologische Beobachtungen beruhen jedoch auf dem Nachweis von leuchtenden Galaxien, die gebiaste Indikatoren (biased tracer) der darunterliegenden Dunklen Materie sind. In dieser Arbeit präsentiere ich Rekonstruktionen des kosmischen Netzes der Dunklen Materie und kosmischer Geschwindigkeitsfelder. Beide Aspekte meiner Arbeit, der theoretische Formalismus und die Ergebnisse der Anwendungen sowohl auf kosmologische Simulationen als auch auf Galaxie-Rotverschiebungssurveys, weden detaiiert aufgeführt. Die Grundlage dieser Methode beruht auf einem statistischen Ansatz, bei dem ein gegebener Galaxienkatalog als eine Realisierung des darunter liegenden Dunklen Materiedichtefeldes interpretiert wird. Unsere Rekonstruktionen werden rechnerisch auf einem Gitter durch das Sampling einer Wahrscheinlichkeitsdichtefunktion durchgeführt, die die gemeinsame a posteriori Wahrscheinlichkeit der Materiedichte und des dreidimensionalen Geschwindigkeitsfeldes beschreibt. Der statistische Hintergrund unserer Methode ist im Kapitel "Implantation of argo" beschrieben, wobei die Einführung in die Samplingmethoden unter besonderer Berücksichtigung der Markov-Kette-Monte-Carlo-Technik erfolgt. Im Kapitel "Phase-Space Reconstructions with N-body Simulations" stelle ich ein neuartiges Biasmodell vor, welches die Galaxienanzahldichte mit der darunter liegenden Dunklen Materiedichte verknüpft. Diesen zerlege ich in einen deterministischen, nicht linearen und skalenabhängigen analytischen Teil und einen stochastischen Teil. Das letztere beschreibe ich durch einen Negativ-Binomial-Likelihood Ausdruck, welches die Abweichungen von Poissonität modelliert. Beide Biaskomponenten wurden bereits theoretisch untersucht, aber bisher noch nie in einem Rekonstruktionsalgorithmus getestet. Ich evaluiere diese neuen Beiträge mit $N$-Körper-Simulationen, um die Verbesserungen zu beurteilen und um zu zeigen, dass der stochastische Bias im Leistungsspektrum bei Wellenzahlen von  k < 0.15 h Mpc^- 1 unabdingbar ist. Im zweiten Teil des Kapitels "Phase-Space Reconstructions with N-body Simulations" beschreibe und validiere ich unseren Ansatz, das kosmische Geschwindigkeitsfeld gemeinsam mit der Dunklen Materiedichte zu rekonstruieren. Ich verwende lineare Störungstheorie für die großräumigen Potentialströme und einen Dispersionsterm, um virialisierte Galaxiebewegungen zu modellieren. Die Ergebnisse zeigen, dass unsere Methode die Rotverschiebungsverzerrungen der Positionen der Galaxien genau beschreibt. Ich analysiere die Ergebnisse sowohl mit dem anisotropen Leistungsspektrum, als auch mit dem zweidimensionalen Leistungsspektrum. Schließlich zeige ich im Kapitel "Phase-space Reconstructions with Galaxy Redshift Surveys", wie ich alle Ergebnisse kombiniere und die Methode auf den CMASS (für Constant (stellar) Mass) Galaxienkatalog anwende. Ich beschreibe, wie unsere Methode die Selektionseffekte der Beobachtungen innerhalb des Rekonstruktionsalgorithmus berücksichtigt. Weiterhin demonstriere ich, dass die Renormalisierung der a priori Verteilung zwingend erforderlich ist, um die Beiträge höherer Ordnung im Strukturbildungsmodell zu berücksichtigen. Außerdem wird ein rotverschiebungsabhängiger Bias-Faktor theoretisch motiviert und in unseren Algorithmus implementiert. Unsere Rekonstruktionen, welche diese verschiedenen Verfeinerungen beinhaten, führen zu robusten Ergebnissen hinsichtlich des Feldes der Dunklen Materie bis zu Skalen von k <0.2 Mpc^-1 im Leistungsspektrum. Außerdem werden Anisotropien in dem rekonstruierten Galaxienkatalog bis zu Abständen von r~20  h^-1 Mpc in der Korrelationsfunktion zu einem hohen Grad überwunden. Wir testen die Ergebnisse unserer kosmischen Geschwindigkeitsrekonstruktion, indem wir sie mit einem synthetischen Mock-Galaxienkatalog vergleichen und bestätigen eine starke Korrelation zwischen den Mock- und den rekonstruierten Geschwindigkeiten. Die Anwendungen sowohl des Dichtefeldes ohne Rotverschiebungsverzerrungen als auch der Geschwindigkeitsrekonstruktionen sind sehr vielfältig und können für verbesserte Analysen der baryonischen akustischen Oszillationen, Umgebungsstudien des kosmischen Netzes, des kinematischen  Sunjajew-Seldowitsch-Effekts oder des integrierten Sachs-Wolfe-Effekts verwendet werden.
KW  - large-scale structure formation
KW  - großräumige Strukturen
KW  - Kosmologie
KW  - Theorie
KW  - cosmology
KW  - theory
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-403565
ER  - 
TY  - THES
A1  - Aue, Lars
T1  - Cyclone impacts on sea ice in the Atlantic Arctic Ocean
T1  - Auswirkungen von Zyklonen auf das Meereis im Atlantischen Arktischen Ozean
N2  - The Arctic is the hot spot of the ongoing, global climate change. Over the last decades, near-surface temperatures in the Arctic have been rising almost four times faster than on global average. This amplified warming of the Arctic and the associated rapid changes of its environment are largely influenced by interactions between individual components of the Arctic climate system. On daily to weekly time scales, storms can have major impacts on the Arctic sea-ice cover and are thus an important part of these interactions within the Arctic climate. The sea-ice impacts of storms are related to high wind speeds, which enhance the drift and deformation of sea ice, as well as to changes in the surface energy budget in association with air mass advection, which impact the seasonal sea-ice growth and melt. 

The occurrence of storms in the Arctic is typically associated with the passage of transient cyclones. Even though the above described mechanisms how storms/cyclones impact the Arctic sea ice are in principal known, there is a lack of statistical quantification of these effects. In accordance with that, the overarching objective of this thesis is to statistically quantify cyclone impacts on sea-ice concentration (SIC) in the Atlantic Arctic Ocean over the last four decades. In order to further advance the understanding of the related mechanisms, an additional objective is to separate dynamic and thermodynamic cyclone impacts on sea ice and assess their relative importance. Finally, this thesis aims to quantify recent changes in cyclone impacts on SIC. These research objectives are tackled utilizing various data sets, including atmospheric and oceanic reanalysis data as well as a coupled model simulation and a cyclone tracking algorithm. 

Results from this thesis demonstrate that cyclones are significantly impacting SIC in the Atlantic Arctic Ocean from autumn to spring, while there are mostly no significant impacts in summer. The strength and the sign (SIC decreasing or SIC increasing) of the cyclone impacts strongly depends on the considered daily time scale and the region of the Atlantic Arctic Ocean. Specifically, an initial decrease in SIC (day -3 to day 0 relative to the cyclone) is found in the Greenland, Barents and Kara Seas, while SIC increases following cyclones (day 0 to day 5 relative to the cyclone) are mostly limited to the Barents and Kara Seas. 
 
For the cold season, this results in a pronounced regional difference between overall (day -3 to day 5 relative to the cyclone) SIC-decreasing cyclone impacts in the Greenland Sea and overall SIC-increasing cyclone impacts in the Barents and Kara Seas. A cyclone case study based on a coupled model simulation indicates that both dynamic and thermodynamic mechanisms contribute to cyclone impacts on sea ice in winter. A typical pattern consisting of an initial dominance of dynamic sea-ice changes followed by enhanced thermodynamic ice growth after the cyclone passage was found. This enhanced ice growth after the cyclone passage most likely also explains the (statistical) overall SIC-increasing effects of cyclones in the Barents and Kara Seas in the cold season.

Significant changes in cyclone impacts on SIC over the last four decades have emerged throughout the year. These recent changes are strongly varying from region to region and month to month. The strongest trends in cyclone impacts on SIC are found in autumn in the Barents and Kara Seas. Here, the magnitude of destructive cyclone impacts on SIC has approximately doubled over the last four decades. The SIC-increasing effects following the cyclone passage have particularly weakened in the Barents Sea in autumn. As a consequence, previously existing overall SIC-increasing cyclone impacts in this region in autumn have recently disappeared. Generally, results from this thesis show that changes in the state of the sea-ice cover (decrease in mean sea-ice concentration and thickness) and near-surface air temperature are most important for changed cyclone impacts on SIC, while changes in cyclone properties (i.e. intensity) do not play a significant role.
N2  - Die Arktis ist der Hotspot des globalen Klimawandels. In den letzten Jahrzehnten sind die oberflächennahen Temperaturen in der Arktis fast viermal so schnell gestiegen wie im globalen Durchschnitt. Diese verstärkte Erwärmung der Arktis und die damit verbundenen raschen Umweltveränderungen werden u.a. durch Wechselwirkungen zwischen den einzelnen Komponenten des arktischen Klimasystems angetrieben. Auf täglichen bis wöchentlichen Zeitskalen können Stürme große Einflüsse auf das arktische Meereis haben und sind somit ein wichtiger Teil dieser Wechselwirkungen innerhalb des arktischen Klimas. Der Einfluss der Stürme auf das Meereis resultiert aus den hohen Windgeschwindigkeiten, welche die Drift und Verformung des Meereises verstärken, sowie aus Änderungen in der Oberflächenenergiebilanz im Zusammenhang mit der Advektion von Luftmassen, was das Wachstum und Schmelzen des Meereises beeinflusst.

Das Auftreten von Stürmen in der Arktis ist oft mit dem Durchzug von Zyklonen verbunden. Obwohl die oben beschriebenen Mechanismen, wie sich Stürme/Zyklone auf das arktische Meereis auswirken, im Prinzip bekannt sind, fehlt es an einer statistischen Quantifizierung dieser Effekte. Dementsprechend ist das übergeordnete Ziel dieser Arbeit eine statistische Quantifizierung der Auswirkungen von Zyklonen auf die Meereiskonzentration (engl. Sea Ice Concentration, SIC) im atlantischen Arktischen Ozeans über die letzten vier Jahrzehnte. Um ein Verständnis für die zugrunde liegenden Mechanismen zu erlangen, besteht ein weiteres Ziel darin, die dynamischen und thermodynamischen Auswirkungen von Zyklonen auf das Meereis zu trennen und ihre relative Bedeutung zu analysieren. Zuletzt zielt diese Arbeit darauf ab, aktuelle Veränderungen der Zykloneneinflüsse auf das Meereis zu quantifizieren. Zum Erreichen dieser Forschungsziele werden verschiedene Datensätze genutzt, darunter atmosphärische und ozeanische Reanalysedaten sowie eine gekoppelte Modellsimulation und ein Algorithmus zur automatischen Identifikation von Zyklonen.

Die Ergebnisse dieser Arbeit zeigen, dass Zyklone die SIC im atlantischen Arktischen Ozean von Herbst bis Frühjahr signifikant beeinflussen, während es im Sommer meist keine signifikanten Auswirkungen gibt. Die Stärke und das Vorzeichen (abnehmende oder zunehmende SIC) der Auswirkungen der Zyklone hängt stark von der betrachteten täglichen Zeitskala und der Region des Arktischen Ozeans ab. So ist ein anfänglicher Rückgang der SIC (Tag -3 bis Tag 0 relativ zum Zyklonendurchgang) in der Grönland-, der Barents- und der Karasee festzustellen, während ein SIC-Anstieg nach dem Zyklonendurchgang (Tag 0 bis Tag 5 relativ zum Zyklonendurchgang) hauptsächlich auf die Barents- und die Karasee beschränkt ist.

Für die kalte Jahreszeit ergibt sich daraus ein ausgeprägter regionaler Unterschied zwischen insgesamt (Tag -3 bis Tag 5 relativ zum Zyklon) SIC-verringernden Zyklonenauswirkungen in der Grönlandsee und insgesamt SIC-erhöhenden Zyklonenauswirkungen in der Barents- und Karasee. Die Analyse spezifischer Zyklonenfälle basierend auf einer gekoppelten Modellsimulation zeigt, dass sowohl dynamische als auch thermodynamische Mechanismen zu den Auswirkungen von Zyklonen auf das Meereis im Winter beitragen. Hierbei wurde ein typisches Muster bestehend aus einer anfänglichen Dominanz dynamischer Meereisveränderungen gefolgt von verstärktem thermodynamischem Eiswachstum nach der Zyklonenpassage gefunden. Dieses verstärkte Eiswachstum nach der Zyklonenpassage erklärt u.a. auch die (statistischen) insgesamt SIC-erhöhenden Effekte von Zyklonen in der Barents- und Karasee im Winter.

Signifikante Änderungen in den Auswirkungen von Zyklonen auf die SIC über die letzten vier Dekaden sind das ganze Jahr über zu finden. Diese Veränderungen variieren stark von Region zu Region und von Monat zu Monat. Die stärksten Trends in den Auswirkungen von Zyklonen auf die SIC sind im Herbst in der Barents- und Karasee zu beobachten. Hier hat sich die Stärke der zerstörerischen Auswirkungen von Zyklonen auf die SIC in den letzten vier Jahrzehnten ungefähr verdoppelt. Die SIC-erhöhenden Effekte nach der Zyklonenpassage haben sich in der Barentssee im Herbst besonders abgeschwächt.  Dadurch sind zuvor existierende, insgesamt SIC-erhöhende Zyklonenauswirkungen in dieser Region und Jahreszeit zuletzt verschwunden. Generell zeigen die Ergebnisse dieser Arbeit, dass Änderungen im Zustand des Meereises (Abnahme der mittleren Meereiskonzentration und -dicke) sowie in der Lufttemperatur die veränderten Auswirkungen der Zyklonen auf die SIC antreiben, während Veränderungen in den Eigenschaften der Zyklonen (z.B. ihre Intensität) keine wesentliche Rolle spielen.
KW  - Arctic
KW  - atmosphere
KW  - sea ice
KW  - cyclones
KW  - meteorology
KW  - Arktis
KW  - Atmosphäre
KW  - Meereis
KW  - Zyklone
KW  - Meteorologie
Y1  - 2024
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-634458
SP  - VIII, 131
ER  - 
TY  - THES
A1  - Avila, Gastón
T1  - Asymptotic staticity and tensor decompositions with fast decay conditions
T1  - Asymptotisch statische Anfangsdaten und Tensor-Zerlegungen mit starken Abfallbedingungen
N2  - Corvino, Corvino and Schoen, Chruściel and Delay have shown the existence of a large class of asymptotically flat vacuum initial data for Einstein's field equations which are static or stationary in a neighborhood of space-like infinity, yet quite general in the interior. The proof relies on some abstract, non-constructive arguments which makes it difficult to calculate such data numerically by using similar arguments. A quasilinear elliptic system of equations is presented of which we expect that it can be used to construct vacuum initial data which are asymptotically flat, time-reflection symmetric, and asymptotic to static data up to a prescribed order at space-like infinity. A perturbation argument is used to show the existence of solutions. It is valid when the order at which the solutions approach staticity is restricted to a certain range. Difficulties appear when trying to improve this result to show the existence of solutions that are asymptotically static at higher order. The problems arise from the lack of surjectivity of a certain operator. Some tensor decompositions in asymptotically flat manifolds exhibit some of the difficulties encountered above. The Helmholtz decomposition, which plays a role in the preparation of initial data for the Maxwell equations, is discussed as a model problem. A method to circumvent the difficulties that arise when fast decay rates are required is discussed. This is done in a way that opens the possibility to perform numerical computations. The insights from the analysis of the Helmholtz decomposition are applied to the York decomposition, which is related to that part of the quasilinear system which gives rise to the difficulties. For this decomposition analogous results are obtained. It turns out, however, that in this case the presence of symmetries of the underlying metric leads to certain complications. The question, whether the results obtained so far can be used again to show by a perturbation argument the existence of vacuum initial data which approach static solutions at infinity at any given order, thus remains open. The answer requires further analysis and perhaps new methods.
N2  - Corvino, Corvino und Schoen als auch Chruściel und Delay haben die Existenz einer grossen Klasse asymptotisch flacher Anfangsdaten für Einsteins Vakuumfeldgleichungen gezeigt, die in einer Umgebung des raumartig Unendlichen statisch oder stationär aber im Inneren der Anfangshyperfläche sehr allgemein sind. Der Beweis beruht zum Teil auf abstrakten, nicht konstruktiven Argumenten, die Schwierigkeiten bereiten, wenn derartige Daten numerisch berechnet werden sollen. In der Arbeit wird ein quasilineares elliptisches Gleichungssystem vorgestellt, von dem wir annehmen, dass es geeignet ist, asymptotisch flache Vakuumanfangsdaten zu berechnen, die zeitreflektionssymmetrisch sind und im raumartig Unendlichen in einer vorgeschriebenen Ordnung asymptotisch zu statischen Daten sind. Mit einem Störungsargument wird ein Existenzsatz bewiesen, der gilt, solange die Ordnung, in welcher die Lösungen asymptotisch statische Lösungen approximieren, in einem gewissen eingeschränkten Bereich liegt. Versucht man, den Gültigkeitsbereich des Satzes zu erweitern, treten Schwierigkeiten auf. Diese hängen damit zusammen, dass ein gewisser Operator nicht mehr surjektiv ist. In einigen Tensorzerlegungen auf asymptotisch flachen Räumen treten ähnliche Probleme auf, wie die oben erwähnten. Die Helmholtzzerlegung, die bei der Bereitstellung von Anfangsdaten für die Maxwellgleichungen eine Rolle spielt, wird als ein Modellfall diskutiert. Es wird eine Methode angegeben, die es erlaubt, die Schwierigkeiten zu umgehen, die auftreten, wenn ein schnelles Abfallverhalten des gesuchten Vektorfeldes im raumartig Unendlichen gefordert wird. Diese Methode gestattet es, solche Felder auch numerisch zu berechnen. Die Einsichten aus der Analyse der Helmholtzzerlegung werden dann auf die Yorkzerlegung angewandt, die in den Teil des quasilinearen Systems eingeht, der Anlass zu den genannten Schwierigkeiten gibt. Für diese Zerlegung ergeben sich analoge Resultate. Es treten allerdings Schwierigkeiten auf, wenn die zu Grunde liegende Metrik Symmetrien aufweist. Die Frage, ob die Ergebnisse, die soweit erhalten wurden, in einem Störungsargument verwendet werden können um die Existenz von Vakuumdaten zu zeigen, die im räumlich Unendlichen in jeder Ordnung statische Daten approximieren, bleibt daher offen. Die Antwort erfordert eine weitergehende Untersuchung und möglicherweise auch neue Methoden.
KW  - Einsteins Feldgleichungen
KW  - Zwangsgleichungen
KW  - Tensor-Zerlegungen
KW  - raumartige Unendliche
KW  - elliptisches Gleichungssystem
KW  - Einstein's field equations
KW  - constraint equations
KW  - tensor decompositions
KW  - space-like infinity
KW  - elliptic systems
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-54046
ER  - 
TY  - JOUR
A1  - Awad, Emad
A1  - Metzler, Ralf
T1  - Crossover dynamics from superdiffusion to subdiffusion
BT  - models and solutions
JF  - Fractional calculus and applied analysis : an international journal for theory and applications
N2  - The Cattaneo or telegrapher's equation describes the crossover from initial ballistic to normal diffusion. Here we study and survey time-fractional generalisations of this equation that are shown to produce the crossover of the mean squared displacement from superdiffusion to subdiffusion. Conditional solutions are derived in terms of Fox H-functions and the dth-order moments as well as the diffusive flux of the different models are derived. Moreover, the concept of the distribution-like is proposed as an alternative to the probability density function.
KW  - Cattaneo equation
KW  - telegrapher's equation
KW  - crossover dynamics
KW  - fractional dynamic equations
KW  - anomalous diffusion
KW  - superdiffusion and
KW  - subdiffusion
KW  - Fox H-functions
Y1  - 2020
U6  - https://doi.org/10.1515/fca-2020-0003
SN  - 1311-0454
SN  - 1314-2224
VL  - 23
IS  - 1
SP  - 55
EP  - 102
PB  - De Gruyter
CY  - Berlin ; Boston
ER  - 
TY  - JOUR
A1  - Awad, Emad
A1  - Metzler, Ralf
T1  - Closed-form multi-dimensional solutions and asymptotic behaviours for subdiffusive processes with crossovers: II. Accelerating case
JF  - Journal of physics : A, Mathematical and theoretical
N2  - Anomalous diffusion with a power-law time dependence vertical bar R vertical bar(2)(t) similar or equal to t(alpha i) of the mean squared displacement occurs quite ubiquitously in numerous complex systems. Often, this anomalous diffusion is characterised by crossovers between regimes with different anomalous diffusion exponents alpha(i). Here we consider the case when such a crossover occurs from a first regime with alpha(1) to a second regime with alpha(2) such that alpha(2) > alpha(1), i.e., accelerating anomalous diffusion. A widely used framework to describe such crossovers in a one-dimensional setting is the bi-fractional diffusion equation of the so-called modified type, involving two time-fractional derivatives defined in the Riemann-Liouville sense. We here generalise this bi-fractional diffusion equation to higher dimensions and derive its multidimensional propagator (Green's function) for the general case when also a space fractional derivative is present, taking into consideration long-ranged jumps (Levy flights). We derive the asymptotic behaviours for this propagator in both the short- and long-time as well the short- and long-distance regimes. Finally, we also calculate the mean squared displacement, skewness and kurtosis in all dimensions, demonstrating that in the general case the non-Gaussian shape of the probability density function changes.
KW  - multidimensional fractional diffusion equation
KW  - continuous time random
KW  - walks
KW  - crossover anomalous diffusion dynamics
KW  - non-Gaussian probability
KW  - density
Y1  - 2022
U6  - https://doi.org/10.1088/1751-8121/ac5a90
SN  - 1751-8113
SN  - 1751-8121
VL  - 55
IS  - 20
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Aydiner, Ekrem
A1  - Cherstvy, Andrey G.
A1  - Metzler, Ralf
T1  - Wealth distribution, Pareto law, and stretched exponential decay of money
BT  - Computer simulations analysis of agent-based models
JF  - Physica : europhysics journal ; A, Statistical mechanics and its applications
N2  - We study by Monte Carlo simulations a kinetic exchange trading model for both fixed and distributed saving propensities of the agents and rationalize the person and wealth distributions. We show that the newly introduced wealth distribution – that may be more amenable in certain situations – features a different power-law exponent, particularly for distributed saving propensities of the agents. For open agent-based systems, we analyze the person and wealth distributions and find that the presence of trap agents alters their amplitude, leaving however the scaling exponents nearly unaffected. For an open system, we show that the total wealth – for different trap agent densities and saving propensities of the agents – decreases in time according to the classical Kohlrausch–Williams–Watts stretched exponential law. Interestingly, this decay does not depend on the trap agent density, but rather on saving propensities. The system relaxation for fixed and distributed saving schemes are found to be different.
KW  - Econophysics
KW  - Wealth and income distribution
KW  - Pareto law
KW  - Scaling exponents
Y1  - 2017
U6  - https://doi.org/10.1016/j.physa.2017.08.017
SN  - 0378-4371
SN  - 1873-2119
VL  - 490
SP  - 278
EP  - 288
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - THES
A1  - Bachmann, Felix
T1  - Non-linearity of magnetic micropropellers
BT  - chances and challenges of complex dynamics at the microscale
Y1  - 2019
ER  - 
TY  - THES
A1  - Baczyński, Krzysztof Konrad
T1  - Buckling instabilities of semiflexible filaments in biological systems
T1  - Knickinstabilitäten semiflexibler Filamente in biologischen Systemen
N2  - In dieser Arbeit werden Knickinstabilitäten von Filamenten in biologischen Systemen untersucht. Das Zytoskelett von Zellen ist aus solchen Filamenten aufgebaut. Sie sind für die mechanische Stabilität der Zelle verantwortlich und spielen eine große Rolle bei intrazellulären Transportprozessen durch molekulare Motoren, die verschiedene Lasten wie beispielsweise Organellen entlang der Filamente des Zytoskeletts transportieren. Filamente sind semiflexible Polymere, deren Biegeenergie ähnlich groß ist wie die thermische Energie, so dass sie auch als elastische Balken auf der Nanoskala gesehen werden können, die signifikante thermische Fluktuationen zeigen. Wie ein makroskopischer elastischer Balken können auch Filamente eine mechanische Knickinstabilität unter Kompression zeigen. Im ersten Teil dieser Arbeit wird untersucht, wie diese Instabilität durch thermische Fluktuationen der Filamente beeinflusst wird. In Zellen können Kompressionskräfte durch molekulare Motoren erzeugt werden. Das geschieht zum Beispiel während der Zellteilung in der mitotischen Spindel. Im zweiten Teil der Arbeit untersuchen wir, wie die stochastische Natur einer von Motoren generierten Kraft die Knickinstabilität von Filamenten beeinflusst. Zunächst stellen wir kurz das Problem von Knickinstabilitäten auf der makroskopischen Skala dar und führen ein Modell für das Knicken von Filamenten oder elastischen Stäben in zwei Raumdimensionen und in Anwesenheit thermischer Fluktuationen ein. Wir präsentieren eine analytische Lösung für Knickinstabilitäten in Anwesenheit thermischer Fluktuationen, die auf einer Renormierungsgruppenrechnung im Rahmen des nichtlinearen Sigma-Models basiert. Wir integrieren die kurzwelligen Fluktuationen aus, um eine effektive Theorie für die langwelligen Moden zu erhalten, die die Knickinstabilität bestimmen. Wir berechnen die Änderung der kritischen Kraft für die Knickinstabilität und zeigen, dass die thermischen Fluktuationen in zwei Raumdimensionen zu einer Zunahme der kritischen Kraft führen. Außerdem zeigen wir, dass thermische Fluktuationen im geknickten Zustand zu einer Zunahme der mittleren projizierten Länge des Filaments in Richtung der wirkenden Kraft führen. Als Funktion der Konturlänge des Filaments besitzt die mittlere projizierte Länge eine Spitze an der Knickinstabilität, die durch thermische Fluktuationen abgerundet wird. Unser Hauptresultat ist die Beobachtung, dass ein geknicktes Filament unter dem Einfluss thermischer Fluktuationen gestreckt wird, d.h. dass seine mittlere projizierte Länge in Richtung der Kompressionskraft auf Grund der thermischen Fluktuationen zunimmt. Unsere analytischen Resultate werden durch Monte-Carlo Simulationen der Knickinstabilität semiflexibler Filamente in zwei Raumdimensionen bestätigt. Wir führen auch Monte-Carlo Simulationen in höheren Raumdimensionen durch und zeigen, dass die Zunahme der projizierten Länge unter dem Einfluss thermischer Fluktuationen weniger ausgeprägt ist und stark von der Wahl der Randbedingungen abhängt. Im zweiten Teil der Arbeit formulieren wir ein Modell für die Knickinstabilität semiflexibler Filamente unter dem Einfluss molekularer Motoren. Wir untersuchen ein System, in dem sich eine Gruppe von Motoren entlang eines fixierten Filaments bewegt, und dabei ein zweites Filament als Last trägt. Das Last-Filament wird gegen eine Wand gedrückt und knickt. Während des Knickvorgangs können die Motoren, die die Kraft auf das Filament generieren, stochastisch von dem Filament ab- und an das Filament anbinden. Wir formulieren ein stochastisches Model für dieses System und berechnen die “mean first passage time“, d.h. die mittlere Zeit für den Übergang von einem Zustand, in dem alle Motoren gebundenen sind zu einem Zustand, in dem alle Motoren abgebunden sind. Dieser Übergang entspricht auch einem Übergang aus dem gebogenen zurück in einen ungebogenen Zustand des Last-Filaments. Unser Resultat zeigt, dass für genügend kurze Mikrotubuli die Bewegung der Motoren von der durch das Last-Filament generierten Kraft beeinflusst wird. Diese Ergebnisse können in zukünftigen Experimenten überprüft werden.
N2  - We study buckling instabilities of filaments in biological systems. Filaments in a cell are the building blocks of the cytoskeleton. They are responsible for the mechanical stability of cells and play an important role in intracellular transport by molecular motors, which transport cargo such as organelles along cytoskeletal filaments. Filaments of the cytoskeleton are semiflexible polymers, i.e., their bending energy is comparable to the thermal energy such that they can be viewed as elastic rods on the nanometer scale, which exhibit pronounced thermal fluctuations. Like macroscopic elastic rods, filaments can undergo a mechanical buckling instability under a compressive load. In the first part of the thesis, we study how this buckling instability is affected by the pronounced thermal fluctuations of the filaments. In cells, compressive loads on filaments can be generated by molecular motors. This happens, for example, during cell division in the mitotic spindle. In the second part of the thesis, we investigate how the stochastic nature of such motor-generated forces influences the buckling behavior of filaments. In chapter 2 we review briefly the buckling instability problem of rods on the macroscopic scale and introduce an analytical model for buckling of filaments or elastic rods in two spatial dimensions in the presence of thermal fluctuations. We present an analytical treatment of the buckling instability in the presence of thermal fluctuations based on a renormalization-like procedure in terms of the non-linear sigma model where we integrate out short-wavelength fluctuations in order to obtain an effective theory for the mode of the longest wavelength governing the buckling instability. We calculate the resulting shift of the critical force by fluctuation effects and find that, in two spatial dimensions, thermal fluctuations increase this force. Furthermore, in the buckled state, thermal fluctuations lead to an increase in the mean projected length of the filament in the force direction. As a function of the contour length, the mean projected length exhibits a cusp at the buckling instability, which becomes rounded by thermal fluctuations. Our main result is the observation that a buckled filament is stretched by thermal fluctuations, i.e., its mean projected length in the direction of the applied force increases by thermal fluctuations. Our analytical results are confirmed by Monte Carlo simulations for buckling of semiflexible filaments in two spatial dimensions. We also perform Monte Carlo simulations in higher spatial dimensions and show that the increase in projected length by thermal fluctuations is less pronounced than in two dimensions and strongly depends on the choice of the boundary conditions. In the second part of this work, we present a model for buckling of semiflexible filaments under the action of molecular motors. We investigate a system in which a group of motors moves along a clamped filament carrying a second filament as a cargo. The cargo-filament is pushed against the wall and eventually buckles. The force-generating motors can stochastically unbind and rebind to the filament during the buckling process. We formulate a stochastic model of this system and calculate the mean first passage time for the unbinding of all linking motors which corresponds to the transition back to the unbuckled state of the cargo filament in a mean-field model. Our results show that for sufficiently short microtubules the movement of kinesin-I-motors is affected by the load force generated by the cargo filament. Our predictions could be tested in future experiments.
KW  - Polymere
KW  - Filament
KW  - Elastizität
KW  - Knickinstabilität
KW  - molekulare Motoren
KW  - Polymers
KW  - filaments
KW  - elasticity
KW  - buckling
KW  - molecular motors
Y1  - 2009
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-37927
ER  - 
TY  - THES
A1  - Balzer, Arnim
T1  - Crab flare observations with H.E.S.S. phase II
T1  - Crab Flare Observations with H.E.S.S. Phase II
N2  - The H.E.S.S. array is a third generation Imaging Atmospheric Cherenkov Telescope (IACT) array. It is located in the Khomas Highland in Namibia, and measures very high energy (VHE) gamma-rays. In Phase I, the array started data taking in 2004 with its four identical 13 m telescopes. Since then, H.E.S.S. has emerged as the most successful IACT experiment to date. Among the almost 150 sources of VHE gamma-ray radiation found so far, even the oldest detection, the Crab Nebula, keeps surprising the scientific community with unexplained phenomena such as the recently discovered very energetic flares of high energy gamma-ray radiation. During its most recent flare, which was detected by the Fermi satellite in March 2013, the Crab Nebula was simultaneously observed with the H.E.S.S. array for six nights. The results of the observations will be discussed in detail during the course of this work. During the nights of the flare, the new 24 m × 32 m H.E.S.S. II telescope was still being commissioned, but participated in the data taking for one night. To be able to reconstruct and analyze the data of the H.E.S.S. Phase II array, the algorithms and software used by the H.E.S.S. Phase I array had to be adapted. The most prominent advanced shower reconstruction technique developed by de Naurois and Rolland, the template-based model analysis, compares real shower images taken by the Cherenkov telescope cameras with shower templates obtained using a semi-analytical model. To find the best fitting image, and, therefore, the relevant parameters that describe the air shower best, a pixel-wise log-likelihood fit is done. The adaptation of this advanced shower reconstruction technique to the heterogeneous H.E.S.S. Phase II array for stereo events (i.e. air showers seen by at least two telescopes of any kind), its performance using MonteCarlo simulations as well as its application to real data will be described.
N2  - Das H.E.S.S. Experiment misst sehr hochenergetische Gammastrahlung im Khomas Hochland von Namibia. Es ist ein sogenanntes abbildendes atmosphärisches Cherenkov-Teleskopsystem welches in der 1. Phase, die im Jahr 2004 mit der Datennahme begann, aus vier identischen 13 m Spiegelteleskopen bestand. Seitdem hat sich H.E.S.S. als das erfolgreichstes Experiment in der bodengebundenen Gammastrahlungsastronomie etabliert. Selbst die älteste der mittlerweile fast 150 entdeckten Quellen von sehr hochenergetischer Gammastrahlung, der Krebsnebel, fasziniert immernoch Wissenschaftler mit neuen bisher unbekannten und unerwarteten Phänomenen. Ein Beispiel dafür sind die vor kurzem entdeckten sehr energiereichen Ausbrüche von hochenergetischer Gammastrahlung. Bei dem letzten deratigen Ausbruch des Krebsnebels im März 2013 hat das H.E.S.S. Experiment für sechs Nächte simultan mit dem Fermi-Satelliten, welcher den Ausbruch entdeckte, Daten genommen. Die Analyse der Daten, deren Ergebnis und deren Interpretation werden im Detail in dieser Arbeit vorgestellt. Während dieser Beobachtungen befand sich ein neues 24 m × 32 m großes Spiegelteleskop, das H.E.S.S. II- Teleskop, noch in seiner Inbetriebnahme, trotzdem hat es für eine dieser sechs Nächte an der Datennahme des gesamten Teleskopsystems teilgenommen. Um die Daten rekonstruieren und analysieren zu können, mussten die für die 1. Phase des Experiments entwickelten Algorithmen und die Software des H.E.S.S.- Experiments angepasst werden. Die fortschrittlichste Schauerrekonstruktionsmethode, welche von de Naurois und Rolland entwickelt wurde, basiert auf dem Vergleich von echten Schauerbildern, die mit Hilfe der Cherenkov-Kameras der einzelnen Teleskope aufgenommen wurden, mit Schauerschablonen die mit Hilfe eines semianalytischen Modells erzeugt wurden. Das am besten passende Bild und damit auch alle relevanten Schauerparameter, wird mit Hilfe einer pixelweisen Loglikelihood-Anpassung ermittelt. Die nötigen Änderungen um Multiteleskopereignisse, welche vom heterogenen H.E.S.S. Phase II Detektor gemessen wurden, mit Hilfe dieser fortschrittlichen Schauerrekonstruktionsmethode analysieren zu können, sowie die resultierenden Ergebnisse von MonteCarlo-Simulationen, als auch die Anwendung auf echte Daten, werden im Rahmen dieser Arbeit präsentiert.
KW  - Gammastrahlungsastronomie
KW  - Rekonstruktionsmethoden
KW  - Datenanalyse
KW  - Krebsnebel
KW  - gamma-ray astronomy
KW  - reconstruction methods
KW  - data analysis
KW  - Crab Nebula
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-72545
ER  - 
TY  - THES
A1  - Banerjee, Abhirup
T1  - Characterizing the spatio-temporal patterns of extreme events
BT  - from recurrence to prediction
N2  - Over the past decades, there has been a growing interest in ‘extreme events’ owing to the increasing threats that climate-related extremes such as floods, heatwaves, droughts, etc., pose to society. While extreme events have diverse definitions across various disciplines, ranging from earth science to neuroscience, they are characterized mainly as dynamic occurrences within a limited time frame that impedes the normal functioning of a system. Although extreme events are rare in occurrence, it has been found in various hydro-meteorological and physiological time series (e.g., river flows, temperatures, heartbeat intervals) that they may exhibit recurrent behavior, i.e., do not end the lifetime of the system. The aim of this thesis to develop some
sophisticated methods to study various properties of extreme events.

One of the main challenges in analyzing such extreme event-like time series is that they have large temporal gaps due to the paucity of the number of observations of extreme events. As a result, existing time series analysis tools are usually not helpful to decode the underlying
information. I use the edit distance (ED) method to analyze extreme event-like time series in their unaltered form. ED is a specific distance metric, mainly designed to measure the similarity/dissimilarity between point process-like data. I combine ED with recurrence plot techniques to identify the recurrence property of flood events in the Mississippi River in the United States. I also use recurrence quantification analysis to show the deterministic properties
and serial dependency in flood events.

After that, I use this non-linear similarity measure (ED) to compute the pairwise dependency in extreme precipitation event series. I incorporate the similarity measure within the framework of complex network theory to study the collective behavior of climate extremes. Under this architecture, the nodes are defined by the spatial grid points of the given spatio-temporal climate dataset. Each node is associated with a time series corresponding to the temporal evolution
of the climate observation at that grid point. Finally, the network links are functions of the pairwise statistical interdependence between the nodes. Various network measures, such as degree, betweenness centrality, clustering coefficient, etc., can be used to quantify the network’s topology. We apply the methodology mentioned above to study the spatio-temporal coherence pattern of extreme rainfall events in the United States and the Ganga River basin, which reveals its relation to various climate processes and the orography of the region.

The identification of precursors associated with the occurrence of extreme events in the near future is extremely important to prepare the masses for an upcoming disaster and mitigate the potential risks associated with such events. Under this motivation, I propose an in-data prediction recipe for predicting the data structures that typically occur prior to extreme events using the Echo state network, a type of Recurrent Neural Network which is a part of the reservoir
computing framework. However, unlike previous works that identify precursory structures in the same variable in which extreme events are manifested (active variable), I try to predict these structures by using data from another dynamic variable (passive variable) which does not show large excursions from the nominal condition but carries imprints of these extreme events. Furthermore, my results demonstrate that the quality of prediction depends on the magnitude
of events, i.e., the higher the magnitude of the extreme, the better is its predictability skill. I show quantitatively that this is because the input signals collectively form a more coherent pattern for an extreme event of higher magnitude, which enhances the efficiency of the machine to predict the forthcoming extreme events.
N2  - In den letzten Jahrzehnten hat das Interesse an ‘Extremereignissen’ aufgrund der zunehmenden Bedrohung, die klimabedingte Extreme wie Überschwemmungen, Hitzewellen, Dürren usw. für die Gesellschaft darstellen, zugenommen. Obwohl Extremereignisse in verschiedenen Disziplinen - von der Geowissenschaft bis zu den Neurowissenschaften - unterschiedlich definiert werden, werden sie hauptsächlich als dynamische Ereignisse innerhalb eines begrenzten Zeitrahmens
charakterisiert, die das normale Funktionieren eines Systems beeinträchtigen. Obwohl Extremereignisse selten vorkommen, wurde festgestellt, dass verschiedene hydro-meteorologische und physiologische Zeitreihen (z. B. Stromabflussmengen, Temperaturen, Herzschlagintervalle) rekurrentes Verhalten. Das heißt, sie enden nicht an der Lebensdauer des Systems. Das Ziel dieser Arbeit ist es, fortschrittliche Methoden zur Untersuchung verschiedener Eigenschaften
von Extremereignissen zu entwickeln.

Eine der größten Herausforderungen bei der Analyse solcher extremen Ereignisse ist, dass sie große zeitliche Lücken aufweisen, da die Anzahl beobachteter Extremereignissen gering ist. Bestehende Zeitreihenanalysetools sind daher in der Regel nicht hilfreich, um die zugrundeliegenden Informationen zu entschlüsseln. Ich verwende die Edit-Distanz (ED) Methode, um extremeereignisähnliche Zeitreihen in ihrer unveränderten Form zu analysieren. ED ist eine spezielle Abstandsmetrik, die hauptsächlich zur Messung der Ähnlichkeit/Unähnlichkeit zwischen punktprozessähnlichen Daten entwickelt wurde. Ich kombiniere ED mit Rekurrenzplots, um die Wiederkehr-Eigenschaften von Hochwasserereignissen am Mississippi in den Vereinigten
Staaten zu ermitteln. Außerdem werte ich die Wiederkehr-Eigenschaften quantitativ aus, um die deterministische Charakteristik und die serielle Abhängigkeit bei Hochwasserereignissen aufzuzeigen.

Anschließend verwende ich dieses nichtlineare Ähnlichkeitsmaß(ED), um die paarweise Abhängigkeit in extremen Niederschlagsereignisreihen zu berechnen. Ich verknüpfe das Ähnlichkeitsmaß mit der Theorie komplexer Netzwerke, um das kollektive Verhalten von Klimaextremen zu untersuchen. In diesem Fall werden die Knoten durch die räumlichen Gitterpunkte des zu untersuchenden raumzeitlichen Klimadatensatzes definiert. Jeder Knoten repräsentiert eine Zeitreihe, die die zeitliche Entwicklung der Klimabeobachtung an diesem Gitterpunkt beschreibt. Schließlich sind die Netzwerkverbindungen Funktionen der paarweisen statistischen Interdependenz zwischen den Knotenpunkten. Zur Quantifizierung der Netztopologie können verschiedene Netzwerkmaße wie unter anderem der Grad, die Betweenness-Zentralität, oder der Clustering-Koeffizient verwendet werden. Wir wenden die oben erwähnte Methodik an, um das raumzeitliche Kohärenzmuster extremer Niederschlagsereignisse in den Vereinigten Staaten und im Einzugsgebiet des Ganges zu untersuchen. Die Ergebnisse zeigen, dass ein Zusammenhang zwischen dem Kohärenzmuster und verschiedenen Klimaprozessen und der Orographie der Region besteht.

Die Identifizierung von Vorläufern, die mit dem Auftreten von Extremereignissen in naher
Zukunft verbunden sind, ist äußerst wichtig, um die Bevölkerung auf eine bevorstehende Katastrophe vorzubereiten und potenziell resultierende Risiken zu mindern. Deshalb schlage ich ein datenbasiertes Vorhersageverfahren zur Bestimmung der Datenstrukturen vor, die typischerweise vor extremen Ereignissen auftreten. Das Verfahren basiert auf dem Echo-State Netzwerk, einem rekurrenten neuronalen Netz, das dem Reservoir-Computing zugeordnet wird. Im Gegensatz zu früheren Arbeiten, die Vorläuferstrukturen in der Variablen identifizieren, in der sich Extremereignisse manifestieren (aktive Variable), versuche ich die Strukturen anhand anderer dynamischer Variablen (passive Variablen) vorherzusagen. Diese Variablen weichen selbst nicht sonderlich von ihrem eigenen Sollzustand ab, aber sie besitzen eine Aussagekraft gegenüber den Extremereignissen. Meine Ergebnisse zeigen, dass die Qualität der Vorhersage von der Magnitude der Ereignisse abhängt, d.h. je extremer ein Ereignis ist, desto besser kann es vorhergesagt werden. Ich belege quantitativ, dass dieser Zusammenhang darauf basiert, dass die gesammelten Eingangssignale aussagekräftigere Kohärenzmuster für Extremereignisse hoher Magnitude bilden. Dies erhöht die Wirksamkeit des Ansatzes bei der Vorhersage bevorstehender Extremereignisse.
KW  - extreme events
KW  - Extremereignisse
KW  - floods
KW  - extreme precipitation
KW  - edit distance
KW  - recurrence plot
KW  - complex network
KW  - echo state network
KW  - Überschwemmungen
KW  - Extremniederschläge
KW  - Edit-Distanz
KW  - Rekurrenzplot
KW  - komplexes Netzwerk
KW  - Echo-State Netzwerk
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-559839
ER  - 
TY  - THES
A1  - Bange, Sebastian
T1  - Transient optical and electrical effects in polymeric semiconductors
T1  - Transiente optische und elektrische Effekte in polymeren Halbeitern
N2  - Classical semiconductor physics has been continuously improving electronic components such as diodes, light-emitting diodes, solar cells and transistors based on highly purified inorganic crystals over the past decades. Organic semiconductors, notably polymeric, are a comparatively young field of research, the first light-emitting diode based on conjugated polymers having been demonstrated in 1990. Polymeric semiconductors are of tremendous interest for high-volume, low-cost manufacturing ("printed electronics"). Due to their rather simple device structure mostly comprising only one or two functional layers, polymeric diodes are much more difficult to optimize compared to small-molecular organic devices. Usually, functions such as charge injection and transport are handled by the same material which thus needs to be highly optimized. The present work contributes to expanding the knowledge on the physical mechanisms determining device performance by analyzing the role of charge injection and transport on device efficiency for blue and white-emitting devices, based on commercially relevant spiro-linked polyfluorene derivatives. It is shown that such polymers can act as very efficient electron conductors and that interface effects such as charge trapping play the key role in determining the overall device efficiency. This work contributes to the knowledge of how charges drift through the polymer layer to finally find neutral emissive trap states and thus allows a quantitative prediction of the emission color of multichromophoric systems, compatible with the observed color shifts upon driving voltage and temperature variation as well as with electrical conditioning effects. In a more methodically oriented part, it is demonstrated that the transient device emission observed upon terminating the driving voltage can be used to monitor the decay of geminately-bound species as well as to determine trapped charge densities. This enables direct comparisons with numerical simulations based on the known properties of charge injection, transport and recombination. The method of charge extraction under linear increasing voltages (CELIV) is investigated in some detail, correcting for errors in the published approach and highlighting the role of non-idealized conditions typically present in experiments. An improved method is suggested to determine the field dependence of charge mobility in a more accurate way. Finally, it is shown that the neglect of charge recombination has led to a misunderstanding of experimental results in terms of a time-dependent mobility relaxation.
N2  - Klassische Halbleiterphysik beschäftigt sich bereits seit mehreren Jahrzehnten erfolgreich mit der Weiterentwicklung elektronischer Bauteile wie Dioden, Leuchtdioden, Solarzellen und Transistoren auf der Basis von hochreinen anorganischen Kristallstrukturen. Im Gegensatz hierzu ist das Forschungsgebiet der organischen, insbesondere der polymeren Halbleiter noch recht jung: Die erste Leuchtdiode auf der Basis von "leitfähigem Plastik" wurde erst 1990 demonstriert. Polymere Halbleiter sind hierbei von besonderem Interesse für hochvolumige Anwendungen im Beleuchtungsbereich, da sie sich kostengünstig herstellen und verarbeiten lassen ("gedruckte Elektronik"). Die vereinfachte Herstellung bedingt dabei eine vergleichsweise geringe Komplexität der Bauteilstruktur und verringert die Optimierungsmöglichkeiten. Die vorliegende Arbeit leistet einen Beitrag zum Verständnis der Vorgänge an Grenzflächen und im Volumen von polymeren Leuchtdioden und ermöglicht damit ein besseres Verständnis der Bauteilfunktion. Im Fokus steht hierbei mit einem spiro-verknüpften Polyfluorenderivat ein kommerziell relevanter Polymertyp, der amorphe und hochgradig temperaturstabile Halbleiterschichten bildet. Ausgehend von einer Charakterisierung der Ladungstransporteigenschaften wird im Zusammenspiel mit numerischen Simulationen der Bauteilemission gezeigt, welche Rolle die polymeren und metallenen Kontaktelektroden für die Bauteilfunktion und -effizienz spielen. Des Weiteren wird ein weiß-emittierendes Polymer untersucht, bei dem die Mischung von blauen, grünen und roten Farbstoffen die Emissionsfarbe bestimmt. Hierbei wird das komplexe Wechselspiel aus Energieübertrag zwischen den Farbstoffen und direktem Ladungseinfang aufgeklärt. Es wird ein quantitatives Modell entwickelt, das die beobachtete Verschiebung der Emissionsfarbe unter wechselnden elektrischen Betriebsparametern erklärt und zusätzlich die Vorhersage von Temperatur- und elektrischen Konditionierungseffekten ermöglicht. Ausgehend von leicht messbaren Parametern wie Stromstärken und Emissionsspektren ermöglicht es Rückschlüsse auf mikroskopische Vorgänge wie die Diffusion von Ladungen hin zu Farbstoffen. Es wird gezeigt, dass im Gegensatz zu bisherigen Erkenntnissen der Ladungseinfang durch Drift im elektrischen Feld gegenüber der Diffusion überwiegt. In einem eher methodisch orientierten Teil zeigt die Arbeit, wie die beim Abschalten von Leuchtdioden beobachtbare Emission dazu verwendet werden kann, Erkenntnisse zu Ladungsdichten während der Betriebsphase zu gewinnen. Es wird abschließend nachgewiesen, dass eine gängige Methode zur Bestimmung von Ladungsbeweglichkeiten unter typischen Messbedingungen fehlerbehaftet ist. Ergebnisse, die bisher als eine zeitliche Relaxation der Beweglichkeit in ungeordneten Halbleitern interpretiert wurden, können damit auf die Rekombination von Ladungen während der Messung zurückgeführt werden. Es wird außerdem gezeigt, dass eine Modifikation der bei der Auswertung verwendeten Analytik die genauere Vermessung der Feldstärkeabhängigkeit der Beweglichkeit ermöglicht.
KW  - Organische Halbleiter
KW  - Ladungstransport
KW  - OLED
KW  - Polymer Electronics
KW  - Organic Semiconductors
KW  - Charge Transport
KW  - OLED
KW  - Polymerelektronik
Y1  - 2009
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-36314
ER  - 
TY  - JOUR
A1  - Baptista, Murilo da Silva
A1  - Grebogi, Celso
A1  - Koberle, Roland
T1  - Dynamically multilayered visual system of the multifractal fly
JF  - Physical review letters
Y1  - 2006
U6  - https://doi.org/10.1103/PhysRevLett.97.178102
SN  - 0031-9007
VL  - 97
IS  - 17
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Baran, Andrzej S.
A1  - Ostensen, R. H.
A1  - Telting, J. H.
A1  - Vos, Joris
A1  - Kilkenny, D.
A1  - Vuckovic, Maja
A1  - Reed, M. D.
A1  - Silvotti, R.
A1  - Jeffery, C. Simon
A1  - Parsons, Steven G.
A1  - Dhillon, V. S.
A1  - Marsh, T. R.
T1  - Pulsations and eclipse-time analysis of HW Vir
JF  - Monthly notices of the Royal Astronomical Society
N2  - We analysed recent K2 data of the short-period eclipsing binary system HW Vir, which consists of a hot subdwarf-B type primary with an M-dwarf companion. We determined the mid-times of eclipses, calculated O-C diagrams, and an average shift of the secondary minimum. Our results show that the orbital period is stable within the errors over the course of the 70 days of observations. Interestingly, the offset from mid-orbital phase between the primary and the secondary eclipses is found to be 1.62 s. If the shift is explained solely by light-travel time, the mass of the sdB primary must be 0.26 M-circle dot, which is too low for the star to be core-helium burning. However, we argue that this result is unlikely to be correct and that a number of effects caused by the relative sizes of the stars conspire to reduce the effective light-travel time measurement. After removing the flux variation caused by the orbit, we calculated the amplitude spectrum to search for pulsations. The spectrum clearly shows periodic signal from close to the orbital frequency up to 4600 mu Hz, with the majority of peaks found below 2600 mu Hz. The amplitudes are below 0.1 part-per-thousand, too low to be detected with ground-based photometry. Thus, the high-precision data from the Kepler spacecraft has revealed that the primary of the HW Vir system is a pulsating sdBV star. We argue that the pulsation spectrum of the primary in HW Vir differs from that in other sdB stars due to its relatively fast rotation that is (nearly) phase-locked with the orbit.
KW  - binaries: eclipsing
KW  - stars: oscillations
KW  - subdwarfs
Y1  - 2019
U6  - https://doi.org/10.1093/mnras/sty2473
SN  - 0035-8711
SN  - 1365-2966
VL  - 481
IS  - 2
SP  - 2721
EP  - 2735
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Baran, Andrzej S.
A1  - Telting, J. H.
A1  - Jeffery, C. Simon
A1  - Ostensen, R. H.
A1  - Vos, Joris
A1  - Reed, M. D.
A1  - Vŭcković, Maja
T1  - K2 observations of the sdBV plus dM/bd binaries PHL457 and EQPsc
JF  - Monthly notices of the Royal Astronomical Society
N2  - We present an analysis of two pulsating subdwarf B stars PHL 457 and EQ Psc observed during the K2 mission. The K2 light curves of both stars show variation consistent with irradiation of a cooler companion by the hot subdwarf. They also show higher frequency oscillations consistent with pulsation. Using new spectroscopic data, we measured the radial velocity, effective temperature, surface gravity, and helium abundance of both hot subdwarfs as a function of orbital phase. We confirm the previously published spectroscopic orbit of PHL 457, and present the first spectroscopic orbit of EQ Psc. The orbital periods are 0.313 and 0.801 d, respectively. For EQPsc, we find a strong correlation between T-eff and orbital phase, due to contribution of light from the irradiated companion. We calculated amplitude spectra, identified significant pulsation frequencies, and searched for multiplets and asymptotic period spacings. By means of multiplets and period spacing, we identified the degrees of several pulsation modes in each star. The g-mode multiplets indicate subsynchronous core rotation with periods of 4.6 d (PHL 457) and 9.4 d (EQ Psc). We made spectral energy disctribution (SED) fits of PHL 457 and EQ Psc using available broad-band photometry and Gaia data. While the SED of PHL 457 shows no evidence of a cool companion, the SED for EQPsc clearly shows an infrared (IR) access consistent with a secondary with a temperature of about 6800K and a radius of 0.23 R-circle dot. This is the first detection of an IR access in any sdB + dM binary.
KW  - binaries: general
KW  - stars: individual (PHL 457, EQ Psc)
KW  - stars: oscillations (including pulsations)
Y1  - 2019
U6  - https://doi.org/10.1093/mnras/stz2209
SN  - 0035-8711
SN  - 1365-2966
VL  - 489
IS  - 2
SP  - 1556
EP  - 1571
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - THES
A1  - Bartel, Melanie
T1  - Kernresonanz-Strukturuntersuchungen an alternativen Precursoren und deren Zwischenprodukten für die Herstellung von Carbonfasern für den Massenmarkt
T1  - Nuclear magnetic resonance structure analyses of alternative precursors and their intermediates for the manufacture of carbon fibers for the mass market
N2  - Carbonfasern haben sich in der Luft- und Raumfahrt etabliert und gewinnen in Alltagsanwendungen wie dem Automobilbereich, Windkraft- und Sportbereich durch ihre hohen Zugfestigkeiten, insbesondere ihrer hohen E-Moduli, und ihrer geringen Dichte immer mehr an Bedeutung. Auf Grund ihrer hohen Kosten, welche sich zur Hälfte aus der Precursorherstellung, inklusive seiner Synthese und seinem Verspinnprozess, dem Lösungsspinnverfahren, ergeben, erhalten zunehmend alternative und schmelzspinnbare Precursoren Interesse. Für die Carbonfaserherstellung wird fast ausschließlich Polyacrylnitril (PAN) verwendet, das vor dem Schmelzen irreversible exotherme Zyklisierungsreaktionen aufweist, welchen sich seine Zersetzung anschließt. Eine Möglichkeit der Reduzierung der Schmelztemperatur von Polymeren ist die Einbringung von Comonomeren zur Erhöhung des freien Volumens und die Reduzierung der intermolekularen Wechselwirkungen als interne Weichmacher. Wie am Fraunhofer IAP gezeigt wurde, kann mittels 2-Methoxyethylacrylat (MEA) die Schmelztemperatur zu neuartigen PAN-basierten Precursoren verringert werden. Um den PAN-co-MEA-Precursor für die nachfolgenden Prozessschritte der Carbonfaserherstellung zu verwenden, müssen die thermoplastischen Fasern in thermisch stabile Fasern ohne thermoplastisches Verhalten überführt werden. Es wurde ein neuer Prozessschritt (Prästabilisierung) eingeführt, welcher unter alkalischen Bedingungen zur Abspaltung der Comonomerseitenkette führt. Neben der Esterhydrolyse finden Reaktionen statt, welche an diesem Material noch nicht hinreichend untersucht wurden. Weiterhin stellt sich die Frage nach der Kinetik der Prästabilisierung und der Ermittlung einer geeigneten Prozessführung.

Hierzu wurde die Prästabilisierung in den Labormaßstab überführt und die möglichen Zusammensetzungen des aus DMSO und einer KOH-Lösung bestehenden Reaktionsmediums evaluiert. Weiterhin wurde die Behandlung bei verschiedenen Prästabilisierungszeiten von maximal 30 min und Temperaturen von 40, 50 und 60 °C durchgeführt, um primär mittels NMR-Spektroskopie die chemischen Strukturänderungen aufzuklären. Die Esterhydrolyse des Comonomers, welche zur Abspaltung des 2-Methoxyethanols führt, wurde mittels 1H-NMR-spektroskopischer Untersuchungen detektiert. 

Es wurde ein Modell aufgestellt, das die chemisch-physikalischen Strukturänderungen während der Prästabilisierung aufzeigt. Die zuerst ablaufende Reaktion ist die Esterhydrolyse am Comonomer, welche vom Faserrand nach innen verläuft und durch die Präsenz des DMSO in Kombination mit der KOH-Lösung (Superbase) initiiert wird. Der zeitliche Reaktionsverlauf der Esterhydrolyse kann in drei Bereiche eingeteilt werden. Der erste Bereich ab dem Prästabilisierungsbeginn wird durch die Diffusion der basischen Anionen in die Faser, der zweite Bereich durch die Reaktion an der Estergruppe des Comonomers und der dritte Bereich durch letzte Reaktionen im Faserinneren und diffusiven Prozessen der Produkte und Edukte charakterisiert. Der zweite Bereich kann mit einer Reaktion pseudo 1. Ordnung abgebildet werden, da in diesem Bereich bereits eine ausreichende Diffusion der Edukte in die Faser stattgefunden hat. Bei 50 °C spielt die Diffusion im ersten Bereich im Vergleich zur Reaktion eine untergeordnete Rolle. Mit Erhöhung der Temperatur auf 60 °C kann eine im Verhältnis geringere Diffusions- als Reaktionsgeschwindigkeit beobachtet werden. Die Nebenreaktionen wurden mittels 13C-CP/MAS-NMR-spektroskopischen, elementaranlaytischen Untersuchungen sowie Doppelbrechungsmessungen charakterisiert. Während der alkalischen Esterhydrolyse beginnt die Reduzierung der Nitrilgruppen unter der Bildung von primären Carbonsäureamiden und Carbonsäuren. Zur Beschreibung dieser Umsetzung wurde eine Methode entwickelt, welche die Addition von 13C-CP/MAS-NMR-Spektren der Modellsubstanzen PAN, PAM und PAA beinhaltet. Weitere stattfindende Reaktionen sind die Bildung von konjugierten Doppelbindungen, welche insbesondere auf eine Zyklisierung der Nitrile hinweisen. Die nasschemisch initiierte Zyklisierung der Nitrilgruppen kann zu kürzeren Stabilisierungszeiten und einem besser kontrollierbaren Stabilisierungsprozess durch geringere Wärmefreisetzung und schlussendlich zu einer Kostenersparnis des gesamten Verfahrens führen. Die Umsetzung der Nitrilgruppen konnte mit einer Reaktion pseudo 1. Ordnung gut abgebildet werden. DMSO initiiert die Esterhydrolyse, wobei die KOH-Konzentration einen höheren Einfluss auf die Reaktionsgeschwindigkeit der Ester- und Nitrilhydrolyse als die DMSO-Konzentration besitzt. Beide Reaktionen zeigen eine vergleichbare Abhängigkeit von der Temperatur. Die Erhöhung der Prästabilisierungszeit und der KOH- bzw. DMSO-Konzentration führt zur Migration niedermolekularer Bestandteile des Fasermaterials an die Oberfläche und der Bildung punktueller Ablagerungen bis hin zu miteinander verbundenen Einzelfasern. Eine weitere Erhöhung der Prästabilisierungszeit bzw. der Konzentration führt zu einem steigenden Carbonsäureanteil und zur Quellung des Fasermaterials, wodurch die Ablagerungen in das Reaktionsmedium diffundieren. Die Ablagerungen enthalten Chlor, welches durch den Waschvorgang mit HCl in das Materialsystem gelangt ist und durch Parameteranpassungen reduziert wurde. Die schmelzbaren Fasern konnten durch die Prästabilisierung erfolgreich über eine Kern-Mantel-Struktur in nicht-thermoplastische Fasern überführt werden.

Zur Ermittlung eines geeigneten Prozessfensters für nachfolgende thermische Beanspruchungen der prästabilisierten Fasern wurden drei Kriterien identifiziert, anhand welcher die Evaluation erfolgte. Das erste Kriterium beinhaltet die Notwendigkeit der vollständigen Aufhebung der thermoplastischen Eigenschaft der Fasern. Als zweites Kriterium diente die Fasermorphologie. Anhand von REM-Aufnahmen wurden Faserbündel mit separierten Einzelfasern ohne Ablagerungen für die nachfolgende Stabilisierung ausgewählt. Das dritte Kriterium bezieht sich auf eine möglichst geringe Umsetzung der Nitrilgruppen, um Prästabilisierungsbedingungen mit Nebenreaktionen zu vermeiden. 

Aus den Untersuchungen konnte eine Prästabilisierungstemperatur von 60 °C als geeignet identifiziert werden. Weiterhin führen hoch alkalische Zusammensetzungen des Reaktionsmediums mit KOH-Konzentrationen von 1, 1,5 und 2 M, vorzugsweise 1,5 M und 50 vol% DMSO mit Reaktionszeiten von unter 10 min zu geeigneten Fasern. Ein MEA-Anteil unterhalb von 2 mol% bewirkt eine Überführung in die Unschmelzbarkeit. Thermisch stabile und für die nachfolgende Stabilisierung geeignete Fasern besitzen weiterhin 68 – 80 mol% Nitrilgruppen, 20 – 25 mol% Carbonsäuren, bis zu 15 mol% primäre Carbonsäureamide und zyklisierte Strukturen.
N2  - Carbon fibers have been established in the aerospace industry and gain more importance for daily applications such as in the automotive, wind power or sport sector because of their high tensile strength, high modulus and low density. The high costs of carbon fibers arises from the precursor synthesis and especially from the precursor spinning using wet-spinning, which leads to an increasing interest in alternative and in meltspinable materials as precursors. Polyacrylonitrile (PAN) is used as precursor for carbon fiber manufacture and shows irreversible exothermic cyclic reactions before melting, followed by its decomposition. One possibility to decrease its melting temperature is the use of co-monomers increasing the free volume und reducing the intermolecular interactions acting as internal plasticizers. The Fraunhofer IAP developed a meltspinable PAN-based material with 2-methoxyethylacrylate as co-monomer resulting in new PAN-co-MEA precursor fibers. To use the PAN-co-MEA precursor for carbon fiber production, the thermoplastic fibers have to be converted into non-meltable ones. Therefor a new process step was included named prestabilization, which leads to a scission of the co-monomer side chain. The specific timescale and kinetics of the new process step of prestabilization under alkaline conditions as well as the side reactions are still unclear. Furthermore, a specific parameter set for prestabilization is needed.

For this, the prestabilization was converted into laboratory scale. The reaction medium consists of DMSO and a KOH solution, which were varied in concentration to determine a suitable composition of the reaction medium. Further varied parameters were the reaction time with a maximum of 30 min and a temperature of 40, 50 and 60 °C. The chemical structure changes were primarily determined via NMR spectroscopy. For the study of the alkaline ester hydrolysis of the co-monomer resulting in the cleavage of the side chain, 1H-NMR spectroscopic analysis was used. 

For the chemical and physical structure changes during the prestabilization a model was proposed. The first reaction is the ester hydrolysis from fiber edge to interior initiated by the superbase composed of DMSO and KOH solution. The chronological sequence of MEA reduction can be subdivided in three areas. The first area from the beginning of prestabilization is characterized by the diffusion of the basic anions in the fiber. In the second area the reaction of the ester hydrolysis takes place which can be fitted in this area by a reaction of pseudo 1. order. The third area is characterized by reaction of the last co-monomers and the diffusion of the products out of the fiber. At 50 °C compared to the reaction, the diffusion of the anions into the fiber is a secondary effect. An increase in temperature to 60 °C shifts the diffusion/reaction balance to a higher reaction velocity. The side reactions were detected via 13C-CP/MAS-NMR spectroscopy, elemental analysis and measurements of the birefringence. During the alkaline ester hydrolysis, the nitrile groups reacted to primary carbon acid amides and afterwards to carbon acids. This reaction path was described via a new developed technique consisting of the addition of 13C-CP/MAS-NMR spectra of model substances PAN, PAM and PAA. Further side reactions were the generation of conjugated double bonds, which indicate cyclization. The wet-chemical initiated cyclization of the nitrile groups could lead to shorter stabilization times und a more controllable stabilization process because of less heat release and in the end it could lead to a less expensive process. The sum of overall nitrile reactions could be described with a reaction of pseudo 1. order. The ester hydrolysis is initiated because of the presence of DMSO but the reaction velocity of the ester hydrolysis and the hydrolysis of nitrile groups are more influenced by the KOH concentration than by the DMSO concentration. Both reactions show a similar dependence on temperature. Low-molecular weight components of the precursor migrate out of the fiber to the surface to form punctual deposits with increasing prestabilization time and concentration. These deposits contain chlorine from the washing process with HCl which was reduced with optimized parameters. Because of changed chemical structure with increasing carbon acids the fiber swells and leads to interconnected single fibers without deposits. The meltable fibers were successfully converted to non-meltable ones via a core-shell structure. 

To determine a suitable parameter set of the prestabilization for the subsequent thermal processing step of stabilization, three criteria were identified. The first necessary criterion denotes the thermal stability of the fibers. The second criterion is an unchanged or insignificant changed fiber morphology, respectively. Via the evaluation of SEM images fiber morphologies without deposits and without interconnected single fibers were chosen for a suitable parameter set for subsequent stabilization. The third criterion was a low conversion of the nitrile groups to have precursors with low amount of side reactions. 

The investigations lead to a temperature for prestabilization of 60 °C. Furthermore, reaction media with a high alkaline content of 1, 1.5 and 2 M KOH, especially 1.5 M KOH, with 50 vol% DMSO and reaction times of less than 10 min result in suitable fibers. The MEA content should be less than 2 mol% to convert the meltable in non-meltable fibers. Thermal stable and for the stabilization suitable fibers also contain 68 – 80 mol% nitrile groups, 20 - 25 mol% carbon acids, up to 15 mol% primary carbon acid amides and cyclic structures.
KW  - Carbonfaser Herstellung
KW  - carbon fiber manufacture
KW  - Prästabilisierung
KW  - Hydrolyse
KW  - PAN
KW  - Precursor
KW  - NMR
KW  - prestabilization
KW  - hydrolysis
KW  - PAN
KW  - precursor
KW  - NMR
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-469301
ER  - 
TY  - JOUR
A1  - Basnarkov, Lasko
A1  - Tomovski, Igor
A1  - Sandev, Trifce
A1  - Kocarev, Ljupčo
T1  - Non-Markovian SIR epidemic spreading model of COVID-19
JF  - Chaos, solitons & fractals : applications in science and engineering ; an interdisciplinary journal of nonlinear science
N2  - We introduce non-Markovian SIR epidemic spreading model inspired by the characteristics of the COVID-19, by considering discrete-and continuous-time versions. The distributions of infection intensity and recovery period may take an arbitrary form. By taking corresponding choice of these functions, it is shown that the model reduces to the classical Markovian case. The epidemic threshold is analytically determined for arbitrary functions of infectivity and recovery and verified numerically. The relevance of the model is shown by modeling the first wave of the epidemic in Italy, Spain and the UK, in the spring, 2020.
KW  - Epidemic spreading models
KW  - Non-Markovian processes
KW  - COVID-19
KW  - SIR model
Y1  - 2022
U6  - https://doi.org/10.1016/j.chaos.2022.112286
SN  - 0960-0779
SN  - 1873-2887
VL  - 160
PB  - Elsevier
CY  - Oxford [u.a.]
ER  - 
TY  - THES
A1  - Bastian, Martin
T1  - An emergent machine learning approach for seasonal cyclone activity forecasts
N2  - Seasonal forecasts are of great interest in many areas. Knowing the amount of precipitation for the upcoming season in regions of water scarcity would facilitate a better water management. If farmers knew the weather conditions of the upcoming summer at sowing time, they could select those cereal species that are best adapted to these conditions. This would allow farmers to improve the harvest and potentially even reduce the amount of pesticides used. However, the undoubted advantages of seasonal forecasts are often opposed by their high degree of uncertainty. The great challenge of generating seasonal forecasts with lead times of several months mainly originates from the chaotic nature of the earth system. In a chaotic system, even tiny differences in the initial conditions can lead to strong deviations in the system’s state in the long run.

In this dissertation we propose an emergent machine learning approach for seasonal forecasting, called the AnlgModel. The AnlgModel combines the analogue method with myopic feature selection and bootstrapping. To benchmark the abilities of the AnlgModel we apply it to seasonal cyclone activity forecasts in the North Atlantic and Northwest Pacific. The AnlgModel demonstrates competitive hindcast skills with two operational forecasts and even outperforms these for long lead times.

In the second chapter we comprehend the forecasting strategy of the Anlg-Model. We thereby analyse the analogue selection process for the 2017 North Atlantic and the 2018 Northwest Pacific seasonal cyclone activity. The analysis shows that those climate indices which are known to influence the seasonal cyclone activity, such as the Niño 3.4 SST, are correctly represented among the selected analogues. Furthermore the selected analogues reflect large-scale climate patterns that were identified by expert reports as being determinative for these particular seasons.

In the third chapter we analyse the features that are used by the AnlgModel for its predictions. We therefore inspect the feature relevance (FR). The FR patterns learned by the AnlgModel show a high congruence with the predictor regions used by the operational forecasts. However, the AnlgModel also discovered new features, such as the SST anomaly in the Gulf of Guinea during November. This SST pattern exhibits a remarkably high predictive potential for the upcoming Atlantic hurricane activity.

In the final chapter we investigate potential mechanisms, that link two of these regions with high feature relevance to the Atlantic hurricane activity. We mainly focus on ocean surface transport. The ocean surface flow paths are calculated using Lagrangian particle analysis. We demonstrate that the FR patterns in the region of the Canary islands do not correspond with ocean surface transport. It is instead likely that these FR patterns fingerprint a wind transport of latent heat. The second region to be studied is situated in the Gulf of Guinea. Our analysis shows that the FR patterns seen there do fingerprint ocean surface transport. However, our simulations also show that at least one other mechanism is involved in linking the Gulf of Guinea SST anomaly in November to the hurricane activity of the upcoming season.

In this work the AnlgModel does not only demonstrate its outstanding forecast skills but also shows its capabilities as research tool for detecting oceanic and atmospheric mechanisms.
KW  - seasonal cyclone activity forecasts
Y1  - 2023
ER  - 
TY  - JOUR
A1  - Bastian, Philipp U.
A1  - Yu, Leixiao
A1  - de Guereñu Kurganova, Anna Lopez
A1  - Haag, Rainer
A1  - Kumke, Michael Uwe
T1  - Bioinspired confinement of upconversion nanoparticles for improved performance in aqueous solution
JF  - The journal of physical chemistry : C, Nanomaterials and interfaces
N2  - The resonance energy transfer (RET) from NaYF4:Yb,Er upconverting nanoparticles (UNCPs) to a dye (5-carboxytetramethylrhodamine (TAMRA)) was investigated by photoluminescence experiments and microscale thermophoresis (MST). The dye was excited via RET from the UCNPs which was excited in the near-infrared (NIR). The change of the dye diffusion speed (free vs coupled) was investigated by MST. RET shows significant changes in the decay times of the dye as well as of the UCNPs. MST reveals significant changes in the diffusion speed. A unique amphiphilic coating polymer (customized mussel protein (CMP) polymer) for UCNP surface coating was used, which mimics blood protein adsorption and mussel food protein adhesion to transfer the UCNP into the aqueous phase and to allow surface functionalization. The CMP provides very good water dispersibility to the UCNPs and minimizes ligand exchange and subsequent UCNP aging reactions because of the interlinkage of the CMP on the UCNP surface. Moreover, CMP provides N-3-functional groups for dick chemistry-based functionalization demonstrated with the dye 5-carboxytetramethylrhodamine (TAMRA). This establishes the principle coupling scheme for suitable biomarkers such as antibodies. The CMP provides very stable aqueous UCNP dispersions that are storable up to 3 years in a fridge at 5 degrees C without dissolution or coagulation. The outstanding properties of CMP in shielding the UCNP from unwanted solvent effects is reflected in the distinct increase of the photoluminescence decay times after UCNP functionalization. The UCNP-to-TAMRA energy transfer is also spectroscopically investigated at low temperatures (4-200 K), revealing that one of the two green Er(III) emission bands contributes the major part to the energy transfer. The TAMRA fluorescence decay time increases by a factor of 9500 from 2.28 ns up to 22 mu s due to radiationless energy transfer from the UCNP after NIR excitation of the latter. This underlines the unique properties of CMP as a versatile capping ligand for distinctly improving the UCNPs' performance in aqueous solutions, for coupling of biomolecules, and for applications for in vitro and in vivo experiments using UCNPs as optical probes in life science applications.
Y1  - 2020
U6  - https://doi.org/10.1021/acs.jpcc.0c09798
SN  - 1932-7447
SN  - 1932-7455
VL  - 124
IS  - 52
SP  - 28623
EP  - 28635
PB  - American Chemical Society
CY  - Washington, DC
ER  -