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- radiation mechanisms: non-thermal (15)
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- BL Lacertae objects: individual: PKS 2155-304 (2)
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- BL Lacertae objects: individual: 1ES 1312-423 (1)
- BL Lacertae objects: individual: 1ES 2322-409 (1)
- BL Lacertae objects: individual: AP Librae (1)
- BL Lacertae objects: individual: PKS 0301-243 (1)
- BL Lacertae objects: individual: SHBL J001355.9-185406 (1)
- BL Lacertae objects: individual: lES 0229+200 (1)
- BL Lacertae objects: individual: lES 1101-232 (1)
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- ISM: individual objects: Crab nebula (1)
- ISM: individual objects: HESS J1832-093 (1)
- ISM: individual objects: Puppis A (1)
- ISM: individual objects: SNR G1.9+0.3 (1)
- ISM: individual objects: SNR G22.7-0.2 (1)
- ISM: individual objects: SNR G330.2+1.0 (1)
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- X-rays: individuals: G15.4+0.1 (1)
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- black hole physics (1)
- convection (1)
- dark matter detectors (1)
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- gamma rays: general(HESS J0632+057, VER J0633+057) (1)
- gamma-ray burst: individual: GRB 100621A (1)
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- intergalactic medium (1)
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- pulsars: general (1)
- quasars: individual: 3C 279 (1)
- stars: black holes (1)
- stars: individual: 1FGL J1018.6-5856 (1)
- stars: massive (1)
- stars: winds, outflows (1)
- supernovae: individual: HESS J1818-154 (1)
Institute
Abdalla, H. ; Adam, R. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Angüner, Ekrem Oǧuzhan ; Arcaro, C. ; Armand, C. ; Armstrong, T. ; Ashkar, H. ; Backes, M. ; Baghmanyan, V. ; Martins, V. Barbosa ; Barnacka, A. ; Barnard, M. ; Becherini, Y. ; Berge, D. ; Bernlohr, K. ; Bi, B. ; Bottcher, M. ; Boisson, C. ; Bolmont, J. ; de Lavergne, M. de Bony ; Bordas, Pol ; Breuhaus, M. ; Brun, F. ; Brun, P. ; Bryan, M. ; Buchele, M. ; Bulik, T. ; Bylund, T. ; Caroff, S. ; Carosi, A. ; Casanova, Sabrina ; Chand, T. ; Chandra, S. ; Chen, A. ; Cotter, G. ; Curylo, M. ; Mbarubucyeye, J. Damascene ; Davids, I. D. ; Davies, J. ; Deil, C. ; Devin, J. ; deWilt, P. ; Dirson, L. ; Djannati-Atai, A. ; Dmytriiev, A. ; Donath, A. ; Doroshenko, V. ; Duffy, C. ; Dyks, J. ; Egberts, Kathrin ; Eichhorn, F. ; Einecke, S. ; Emery, G. ; Ernenwein, J. -P. ; Feijen, K. ; Fegan, S. ; Fiasson, A. ; de Clairfontaine, G. Fichet ; Fontaine, G. ; Funk, S. ; Fussling, Matthias ; Gabici, S. ; Gallant, Y. A. ; Giavitto, G. ; Giunti, L. ; Glawion, D. ; Glicenstein, J. F. ; Gottschall, D. ; Grondin, M. -H. ; Hahn, J. ; Haupt, M. ; Hermann, G. ; Hinton, J. A. ; Hofmann, W. ; Hoischen, Clemens ; Holch, T. L. ; Holler, M. ; Horbe, M. ; Horns, D. ; Huber, D. ; Jamrozy, M. ; Jankowsky, D. ; Jankowsky, F. ; Jardin-Blicq, A. ; Joshi, V. ; Jung-Richardt, I. ; Kasai, E. ; Kastendieck, M. A. ; Katarzynski, K. ; Katz, U. ; Khangulyan, D. ; Khelifi, B. ; Klepser, S. ; Kluzniak, W. ; Komin, Nu. ; Konno, R. ; Kosack, K. ; Kostunin, D. ; Kreter, M. ; Lamanna, G. ; Lemiere, A. ; Lemoine-Goumard, M. ; Lenain, J. -P. ; Levy, C. ; Lohse, T. ; Lypova, I. ; Mackey, J. ; Majumdar, J. ; Malyshev, D. ; Malyshev, D. ; Marandon, V. ; Marchegiani, P. ; Marcowith, A. ; Mares, A. ; Marti-Devesa, G. ; Marx, R. ; Maurin, G. ; Meintjes, P. J. ; Meyer, M. ; Mitchell, A. ; Moderski, R. ; Mohamed, M. ; Mohrmann, L. ; Montanari, A. ; Moore, C. ; Morris, P. ; Moulin, E. ; Muller, J. ; Murach, T. ; Nakashima, K. ; Nayerhoda, A. ; de Naurois, M. ; Ndiyavala, H. ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; O'Brien, Patrick ; Odaka, H. ; Ohm, S. ; Olivera-Nieto, L. ; Wilhelmi, E. de Ona ; Ostrowski, M. ; Oya, I. ; Panter, M. ; Panny, S. ; Parsons, R. D. ; Peron, G. ; Peyaud, B. ; Piel, Q. ; Pita, S. ; Poireau, V. ; Noel, A. Priyana ; Prokhorov, D. A. ; Prokoph, H. ; Puhlhofer, G. ; Punch, M. ; Quirrenbach, A. ; Raab, S. ; Rauth, R. ; Reichherzer, P. ; Reimer, A. ; Reimer, O. ; Remy, Q. ; Renaud, M. ; Rieger, F. ; Rinchiuso, L. ; Romoli, C. ; Rowell, G. ; Rudak, B. ; Ruiz-Velasco, E. ; Sahakian, V. ; Sailer, S. ; Sanchez, D. A. ; Santangelo, A. ; Sasaki, M. ; Scalici, M. ; Schussler, F. ; Schutte, H. M. ; Schwanke, U. ; Schwemmer, S. ; Seglar-Arroyo, M. ; Senniappan, M. ; Seyffert, A. S. ; Shafi, N. ; Shiningayamwe, K. ; Simoni, R. ; Sinha, A. ; Sol, H. ; Specovius, A. ; Spencer, S. ; Spir-Jacob, M. ; Stawarz, L. ; Sun, L. ; Steenkamp, R. ; Stegmann, C. ; Steinmassl, S. ; Steppa, C. ; Takahashi, T. ; Tavernier, T. ; Taylor, A. M. ; Terrier, R. ; Tiziani, D. ; Tluczykont, M. ; Tomankova, L. ; Trichard, C. ; Tsirou, M. ; Tuffs, R. ; Uchiyama, Y. ; van der Walt, D. J. ; van Eldik, C. ; van Rensburg, C. ; van Soelen, B. ; Vasileiadis, G. ; Veh, J. ; Venter, C. ; Vincent, P. ; Vink, J. ; Volk, H. J. ; Vuillaume, T. ; Wadiasingh, Z. ; Wagner, S. J. ; Watson, J. ; Werner, F. ; White, R. ; Wierzcholska, A. ; Wong, Yu Wun ; Yusafzai, A. ; Zacharias, M. ; Zanin, R. ; Zargaryan, D. ; Zdziarski, A. A. ; Zech, Alraune ; Zhu, S. J. ; Ziegler, A. ; Zorn, J. ; Zouari, S. ; Zywucka, N.
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.
Abdalla, Hassan E. ; Abramowski, A. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Akhperjanian, A. G. ; Andersson, T. ; Angüner, Ekrem Oǧuzhan ; Arrieta, M. ; Aubert, P. ; Backes, M. ; Balzer, A. ; Barnard, M. ; Becherini, Y. ; Tjus, J. Becker ; Berge, D. ; Bernhard, S. ; Bernlohr, K. ; Blackwell, R. ; Bottcher, M. ; Boisson, C. ; Bolmont, J. ; Bordas, Pol ; Bregeon, J. ; Brun, F. ; Brun, P. ; Bryan, M. ; Bulik, T. ; Capasso, M. ; Carr, J. ; Casanova, Sabrina ; Cerruti, M. ; Chakraborty, N. ; Chalme-Calvet, R. ; Chaves, R. C. G. ; Chen, A. ; Chevalier, J. ; Chretien, M. ; Colafrancesco, S. ; Cologna, G. ; Condon, B. ; Conrad, J. ; Cui, Y. ; Davids, I. D. ; Decock, J. ; Degrange, B. ; Deil, C. ; Devin, J. ; deWilt, P. ; Dirson, L. ; Djannati-Atai, A. ; Domainko, W. ; Donath, A. ; Dubus, G. ; Dutson, K. ; Dyks, J. ; Dyrda, M. ; Edwards, T. ; Egberts, Kathrin ; Eger, P. ; Ernenwein, J. -P. ; Eschbach, S. ; Farnier, C. ; Fegan, S. ; Fernandes, M. V. ; Fiasson, A. ; Fontaine, G. ; Forster, A. ; Funk, S. ; Fussling, Matthias ; Gabici, S. ; Gajdus, M. ; Gallant, Y. A. ; Garrigoux, T. ; Giavitto, G. ; Giebels, B. ; Glicenstein, J. F. ; Gottschal, D. ; Goya, A. ; Grondin, M. -H. ; Hadasch, D. ; Hahn, J. ; Haupt, M. ; Hawkes, J. ; Heinzelmann, G. ; Henri, G. ; Hermann, G. ; Hervet, O. ; Hinton, J. A. ; Hofmann, W. ; Hoischen, Clemens ; Holler, M. ; Horns, D. ; Ivascenko, A. ; Jacholkowska, A. ; Jamrozy, M. ; Janiak, M. ; Jankowsky, D. ; Jankowsky, F. ; Jingo, M. ; Jogler, T. ; Jouvin, L. ; Jung-Richardt, I. ; Kastendieck, M. A. ; Katarzynski, K. ; Katz, U. ; Kerszberg, D. ; Khelifi, B. ; Kieffer, M. ; King, J. ; Klepser, S. ; Klochkov, D. ; Kluzniak, W. ; Kolitzus, D. ; Komin, Nu. ; Kosack, K. ; Krakau, S. ; Kraus, M. ; Krayzel, F. ; Kruger, P. P. ; Laffon, H. ; Lamanna, G. ; Lau, J. ; Lees, J. -P. ; Lefaucheur, J. ; Lefranc, V. ; Lemiere, A. ; Lemoine-Goumard, M. ; Lenain, J. - P. ; Leser, Eva ; Lohse, T. ; Lorentz, M. ; Liu, R. ; Lopez-Coto, R. ; Lypova, I. ; Marandon, V. ; Marcowith, A. ; Mariaud, C. ; Marx, R. ; Maurin, G. ; Maxted, N. ; Mayer, M. ; Meintjes, P. J. ; Meyer, M. ; Mitchell, A. M. W. ; Moderski, R. ; Mohamed, M. ; Mohrmann, L. ; Mora, K. ; Moulin, E. ; Murach, T. ; de Naurois, M. ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; Odaka, H. ; Ottl, S. ; Ohm, S. ; Ostrowski, M. ; Oya, I. ; Padovani, M. ; Panter, M. ; Parsons, R. D. ; Pekeur, N. W. ; Pelletier, G. ; Perennes, C. ; Petrucci, P. -O. ; Peyaud, B. ; Piel, Q. ; Pita, S. ; Poon, H. ; Prokhorov, D. ; Prokoph, H. ; Puhlhofer, G. ; Punch, M. ; Quirrenbach, A. ; Raab, S. ; Reimer, A. ; Reimer, O. ; Renaud, M. ; de los Reyes, R. ; Rieger, F. ; Romoli, C. ; Rosier-Lees, S. ; Rowel, G. ; Rudak, B. ; Rulten, C. B. ; Sahakian, V. ; Salek, D. ; Sanchez, D. A. ; Santangelo, A. ; Sasaki, M. ; Schlickeiser, R. ; Schussler, F. ; Schulz, A. ; Schwanke, U. ; Schwemmer, S. ; Settimo, M. ; Seyffert, A. S. ; Shafi, N. ; Shilon, I. ; Simoni, R. ; Sol, H. ; Spanier, F. ; Spengler, G. ; Spies, F. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Stinzing, F. ; Stycz, K. ; Sushch, I. ; Tavernet, J. -P. ; Tavernier, T. ; Taylor, A. M. ; Terrier, R. ; Tibaldo, L. ; Tiziani, D. ; Tluczykont, M. ; Trichard, C. ; Tuffs, R. ; Uchiyama, Y. ; van der Walt, D. J. ; van Eldik, C. ; van Rensburg, C. ; van Soelen, B. ; Vasileiadis, G. ; Veh, J. ; Venter, C. ; Viana, A. ; Vincent, P. ; Vink, J. ; Voisin, F. ; Volk, H. J. ; Vuillaume, T. ; Wadiasingh, Z. ; Wagner, S. J. ; Wagner, P. ; Wagner, R. M. ; White, R. ; Wierzcholska, A. ; Willmann, P. ; Wornlein, A. ; Wouters, D. ; Yang, R. ; Zabalza, V. ; Zaborov, D. ; Zacharias, M. ; Zanin, R. ; Zdziarski, A. A. ; Zech, Alraune ; Zefi, F. ; Ziegler, A. ; Zywucka, N.
PKS 0625-354 (z = 0.055) was observed with the four High Energy Stereoscopic System (H.E.S.S.) telescopes in 2012 during 5.5 h. The source was detected above an energy threshold of 200 GeV at a significance level of 6.1 sigma. No significant variability is found in these observations. The source is well described with a power-law spectrum with photon index Gamma = 2.84 +/- 0.50(stat) +/- 0.10(syst) and normalization (at E-0 = 1.0 TeV) N-0(E-0)=(0.58 +/- 0.22(stat) +/- 0.12(syst)) x 10(-12) TeV-1 cm(-2) s(-1). Multiwavelength data collected with Fermi-LAT, Swift-XRT, Swift-UVOT, ATOM and WISE are also analysed. Significant variability is observed only in the Fermi-LAT gamma-ray and Swift-XRT X-ray energy bands. Having a good multiwavelength coverage from radio to very high energy, we performed a broad-band modelling from two types of emission scenarios. The results from a one zone lepto-hadronic and a multizone leptonic models are compared and discussed. On the grounds of energetics, our analysis favours a leptonic multizone model. Models associated to the X-ray variability constraint support previous results, suggesting a BL Lac nature of PKS 0625-354 with, however, a large-scale jet structure typical of a radio galaxy.
Abdalla, Hassan E. ; Abramowski, A. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Angüner, Ekrem Oǧuzhan ; Arakawa, M. ; Armand, C. ; Arrieta, M. ; Backes, M. ; Balzer, A. ; Barnard, M. ; Becherini, Y. ; Tjus, J. Becker ; Berge, D. ; Bernhard, S. ; Bernloehr, K. ; Blackwell, R. ; Boettcher, M. ; Boisson, C. ; Bolmont, J. ; Bonnefoy, S. ; Bordas, Pol ; Bregeon, J. ; Brun, F. ; Brun, P. ; Bryan, M. ; Buechele, M. ; Bulik, T. ; Capasso, M. ; Caroff, S. ; Carosi, A. ; Casanova, Sabrina ; Cerruti, M. ; Chakraborty, N. ; Chaves, R. C. G. ; Chen, A. ; Chevalier, J. ; Colafrancesco, S. ; Condon, B. ; Conrad, J. ; Davids, I. D. ; Decock, J. ; Deil, C. ; Devin, J. ; deWilt, P. ; Dirson, L. ; Djannati-Atai, A. ; Donath, A. ; Dyks, J. ; Edwards, T. ; Egberts, Kathrin ; Emery, G. ; Ernenwein, J. -P. ; Eschbach, S. ; Farnier, C. ; Fegan, S. ; Fernandes, M. V. ; Fiasson, A. ; Fontaine, G. ; Funk, S. ; Fuessling, M. ; Gabici, S. ; Gallant, Y. A. ; Garrigoux, T. ; Gate, F. ; Giavitto, G. ; Glawion, D. ; Glicenstein, J. F. ; Gottschall, D. ; Grondin, M. -H. ; Hahn, J. ; Haupt, M. ; Hawkes, J. ; Heinzelmann, G. ; Henri, G. ; Hermann, G. ; Hinton, J. A. ; Hofmann, W. ; Hoischen, Clemens ; Holch, T. L. ; Holler, M. ; Horns, D. ; Ivascenko, A. ; Iwasaki, H. ; Jacholkowska, A. ; Jamrozy, M. ; Jankowsky, D. ; Jankowsky, F. ; Jingo, M. ; Jouvin, L. ; Jung-Richardt, I. ; Kastendieck, M. A. ; Katarzynski, K. ; Katsuragawa, M. ; Katz, U. ; Kerszberg, D. ; Khangulyan, D. ; Khelifi, B. ; King, J. ; Klepser, S. ; Klochkov, D. ; Kluzniak, W. ; Komin, Nu. ; Kosack, K. ; Krakau, S. ; Kraus, M. ; Kruger, P. P. ; Laffon, H. ; Lamanna, G. ; Lau, J. ; Lefaucheur, J. ; Lemiere, A. ; Lemoine-Goumard, M. ; Lenain, J. -P. ; Leser, Eva ; Lohse, T. ; Lorentz, M. ; Liu, R. ; Lopez-Coto, R. ; Lypova, I. ; Malyshev, D. ; Marandon, V. ; Marcowith, A. ; Mariaud, C. ; Marx, R. ; Maurin, G. ; Maxted, N. ; Mayer, M. ; Meintjes, P. J. ; Meyer, M. ; Mitchell, A. M. W. ; Moderski, R. ; Mohamed, M. ; Mohrmann, L. ; Mora, K. ; Moulin, E. ; Murach, T. ; Nakashima, S. ; de Naurois, M. ; Ndiyavala, H. ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; Odaka, H. ; Ohm, S. ; Ostrowski, M. ; Oya, I. ; Padovani, M. ; Panter, M. ; Parsons, R. D. ; Pekeur, N. W. ; Pelletier, G. ; Perennes, C. ; Petrucci, P. -O. ; Peyaud, B. ; Piel, Q. ; Pita, S. ; Poireau, V. ; Prokhorov, D. A. ; Prokoph, H. ; Puehlhofer, G. ; Punch, M. ; Quirrenbach, A. ; Raab, S. ; Rauth, R. ; Reimer, A. ; Reimer, O. ; Renaud, M. ; de los Reyes, R. ; Rieger, F. ; Rinchiuso, L. ; Romoli, C. ; Rowell, G. ; Rudak, B. ; Rulten, C. B. ; Sahakian, V. ; Saito, S. ; Sanchez, D. A. ; Santangelo, A. ; Sasaki, M. ; Schlickeiser, R. ; Schussler, F. ; Schulz, A. ; Schwanke, U. ; Schwemmer, S. ; Seglar-Arroyo, M. ; Seyffert, A. S. ; Shafi, N. ; Shilon, I. ; Shiningayamwe, K. ; Simoni, R. ; Sol, H. ; Spanier, F. ; Spir-Jacob, M. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Steppa, Constantin Beverly ; Sushch, I. ; Takahashi, T. ; Tavernet, J. -P. ; Tavernier, T. ; Taylor, A. M. ; Terrier, R. ; Tibaldo, L. ; Tiziani, D. ; Tluczykont, M. ; Trichard, C. ; Tsirou, M. ; Tsuji, N. ; Tuffs, R. ; Uchiyama, Y. ; van der Walt, D. J. ; van Eldik, C. ; van Rensburg, C. ; van Soelen, B. ; Vasileiadis, G. ; Veh, J. ; Venter, C. ; Viana, A. ; Vincent, P. ; Vink, J. ; Voisin, F. ; Voelk, H. J. ; Vuillaume, T. ; Wadiasingh, Z. ; Wagner, S. J. ; Wagner, P. ; Wagner, R. M. ; White, R. ; Wierzcholska, A. ; Willmann, P. ; Woernlein, A. ; Wouters, D. ; Yang, R. ; Zaborov, D. ; Zacharias, M. ; Zanin, R. ; Zdziarski, A. A. ; Zech, Alraune ; Zefi, F. ; Ziegler, A. ; Zorn, J. ; Zywucka, N. ; Enokiya, R. ; Fukui, Y. ; Hayakawa, T. ; Okuda, T. ; Torii, K. ; Yamamoto, H.
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.
Abdalla, Hassan E. ; Abramowski, A. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Angüner, Ekrem Oǧuzhan ; Arakawa, M. ; Armand, C. ; Arrieta, M. ; Backes, M. ; Balzer, A. ; Barnard, M. ; Becherini, Y. ; Tjus, J. Becker ; Berge, D. ; Bernhard, S. ; Bernloehr, K. ; Blackwell, R. ; Bottcher, M. ; Boisson, C. ; Bolmont, J. ; Bonnefoy, S. ; Bordas, Pol ; Bregeon, J. ; Brun, F. ; Brun, P. ; Bryan, M. ; Buechele, M. ; Bulik, T. ; Capasso, M. ; Caroff, S. ; Carosi, A. ; Casanova, Sabrina ; Cerruti, M. ; Chakraborty, N. ; Chaves, R. C. G. ; Chen, A. ; Chevalier, J. ; Colafrancesco, S. ; Condon, B. ; Conrad, J. ; Davids, I. D. ; Decock, J. ; Deil, C. ; Devin, J. ; deWilt, P. ; Dirson, L. ; Djannati-Atai, A. ; Donath, A. ; Dyks, J. ; Edwards, T. ; Egberts, Kathrin ; Emery, G. ; Ernenwein, J-P ; Eschbach, S. ; Farnier, C. ; Fegan, S. ; Fernandes, M. ; Fiasson, A. ; Fontaine, G. ; Funk, S. ; Fuessling, M. ; Gabici, S. ; Gallant, Y. A. ; Garrigoux, T. ; Gate, F. ; Giavitto, G. ; Glawion, D. ; Glicenstein, J. F. ; Gottschall, D. ; Grondin, M-H ; Hahn, J. ; Haupt, M. ; Hawkes, J. ; Heinzelmann, G. ; Henri, G. ; Hermann, G. ; Hinton, J. A. ; Hofmann, W. ; Hoischen, Clemens ; Holch, T. L. ; Holler, M. ; Horns, D. ; Ivascenko, A. ; Iwasaki, H. ; Jacholkowska, A. ; Jamrozy, M. ; Jankowsky, D. ; Jankowsky, F. ; Jingo, M. ; Jouvin, L. ; Jung-Richardt, I ; Kastendieck, M. A. ; Katarzynski, K. ; Katsuragawa, M. ; Katz, U. ; Kerszberg, D. ; Khangulyan, D. ; Khelifi, B. ; King, J. ; Klepser, S. ; Klochkov, D. ; Kluzniak, W. ; Komin, Nu ; Kosack, K. ; Krakau, S. ; Kraus, M. ; Kruger, P. P. ; Laffon, H. ; Lamanna, G. ; Lau, J. ; Lefaucheur, J. ; Lemiere, A. ; Lemoine-Goumard, M. ; Lenain, J-P ; Leser, Eva ; Lohse, T. ; Lorentz, M. ; Liu, R. ; Lopez-Coto, R. ; Lypova, I ; Malyshev, D. ; Marandon, V ; Marcowith, A. ; Mariaud, C. ; Marx, R. ; Maurin, G. ; Maxted, N. ; Mayer, M. ; Meintjes, P. J. ; Meyer, M. ; Mitchell, A. M. W. ; Moderski, R. ; Mohamed, M. ; Mohrmann, L. ; Mora, K. ; Moulin, E. ; Murach, T. ; Nakashima, S. ; de Naurois, M. ; Ndiyavala, H. ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; Odaka, H. ; Ohm, S. ; Ostrowski, M. ; Oya, I ; Padovani, M. ; Panter, M. ; Parsons, R. D. ; Pekeur, N. W. ; Pelletier, G. ; Perennes, C. ; Petrucci, P-O ; Peyaud, B. ; Piel, Q. ; Pita, S. ; Poireau, V ; Prokhorov, D. A. ; Prokoph, H. ; Puehlhofer, G. ; Punch, M. ; Quirrenbach, A. ; Raab, S. ; Rauth, R. ; Reimer, A. ; Reimer, O. ; Renaud, M. ; de los Reyes, R. ; Rieger, F. ; Rinchiuso, L. ; Romoli, C. ; Rowell, G. ; Rudak, B. ; Rulten, C. B. ; Sahakian, V ; Saito, S. ; Sanchez, D. A. ; Santangelo, A. ; Sasaki, M. ; Schlickeiser, R. ; Schussler, F. ; Schulz, A. ; Schwanke, U. ; Schwemmer, S. ; Seglar-Arroyo, M. ; Seyffert, A. S. ; Shafi, N. ; Shilon, I ; Shiningayamwe, K. ; Simoni, R. ; Sol, H. ; Spanier, F. ; Spir-Jacob, M. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Steppa, Constantin Beverly ; Sushch, Iurii ; Takahashi, T. ; Tavernet, J-P ; Tavernier, T. ; Taylor, A. M. ; Terrier, R. ; Tibaldo, L. ; Tiziani, D. ; Tluczykont, M. ; Trichard, C. ; Tsirou, M. ; Tsuji, N. ; Tuffs, R. ; Uchiyama, Y. ; van der Walt, D. J. ; van Eldik, C. ; van Rensburg, C. ; van Soelen, B. ; Vasileiadis, G. ; Veh, J. ; Venter, C. ; Viana, A. ; Vincent, P. ; Vink, J. ; Voisin, F. ; Voelk, H. J. ; Vuillaume, T. ; Wadiasingh, Z. ; Wagner, S. J. ; Wagner, P. ; Wagner, R. M. ; White, R. ; Wierzcholska, A. ; Willmann, P. ; Woernlein, A. ; Wouters, D. ; Yang, R. ; Zaborov, D. ; Zacharias, M. ; Zanin, R. ; Zdziarski, A. A. ; Zech, Alraune ; Zefi, F. ; Ziegler, A. ; Zorn, J. ; Zywucka, N. ; Magill, J. D. ; Buson, S. ; Cheung, C. C. ; Perkins, J. S. ; Tanaka, Y.
Centaurus A (Cen A) is the nearest radio galaxy discovered as a very-high-energy (VHE; 100 GeV-100 TeV) gamma-ray source by the High Energy Stereoscopic System (H.E.S.S.). It is a faint VHE gamma-ray emitter, though its VHE flux exceeds both the extrapolation from early Fermi-LAT observations as well as expectations from a (misaligned) single-zone synchrotron-self Compton (SSC) description. The latter satisfactorily reproduces the emission from Cen A at lower energies up to a few GeV. New observations with H.E.S.S., comparable in exposure time to those previously reported, were performed and eight years of Fermi-LAT data were accumulated to clarify the spectral characteristics of the gamma-ray emission from the core of Cen A. The results allow us for the first time to achieve the goal of constructing a representative, contemporaneous gamma-ray core spectrum of Cen A over almost five orders of magnitude in energy. Advanced analysis methods, including the template fitting method, allow detection in the VHE range of the core with a statistical significance of 12 sigma on the basis of 213 hours of total exposure time. The spectrum in the energy range of 250 GeV-6 TeV is compatible with a power-law function with a photon index Gamma = 2.52 +/- 0.13(stat) +/- 0.20(sys). An updated Fermi-LAT analysis provides evidence for spectral hardening by Delta Gamma similar or equal to 0.4 +/- 0.1 at gamma-ray energies above 2.8(-0.6)(+1.0) GeV at a level of 4.0 sigma. The fact that the spectrum hardens at GeV energies and extends into the VHE regime disfavour a single-zone SSC interpretation for the overall spectral energy distribution (SED) of the core and is suggestive of a new gamma-ray emitting component connecting the high-energy emission above the break energy to the one observed at VHE energies. The absence of significant variability at both GeV and TeV energies does not yet allow disentanglement of the physical nature of this component, though a jet-related origin is possible and a simple two-zone SED model fit is provided to this end.
Abdalla, Hassan E. ; Abramowski, A. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Angüner, Ekrem Oǧuzhan ; Arakawa, M. ; Arrieta, M. ; Aubert, P. ; Backes, M. ; Balzer, A. ; Barnard, M. ; Becherini, Y. ; Tjus, J. Becker ; Berge, D. ; Bernhard, S. ; Bernloehr, K. ; Blackwell, R. ; Bottcher, M. ; Boisson, C. ; Bolmont, J. ; Bonnefoy, S. ; Bordas, Pol ; Bregeon, J. ; Brun, F. ; Brun, P. ; Bryan, M. ; Buechele, M. ; Bulik, T. ; Capasso, M. ; Caroff, S. ; Carosi, A. ; Carr, J. ; Casanova, Sabrina ; Cerruti, M. ; Chakraborty, N. ; Chaves, R. C. G. ; Chen, A. ; Chevalier, J. ; Colafrancesco, S. ; Condon, B. ; Conrad, J. ; Davids, I. D. ; Decock, J. ; Deil, C. ; Devin, J. ; Dewilt, P. ; Dirson, L. ; Djannati-Atai, A. ; Domainko, W. ; Donath, A. ; Dutson, K. ; Dyks, J. ; Edwards, T. ; Egberts, Kathrin ; Eger, P. ; Emery, G. ; Ernenwein, J-P ; Eschbach, S. ; Farnier, C. ; Fegan, S. ; Fernandes, M. ; Fiasson, A. ; Fontaine, G. ; Foerster, A. ; Funk, S. ; Fuessling, M. ; Gabici, S. ; Gallant, Y. A. ; Garrigoux, T. ; Gate, F. ; Giavitto, G. ; Giebels, B. ; Glawion, D. ; Glicenstein, J. F. ; Gottschall, D. ; Grondin, M-H ; Hahn, J. ; Haupt, M. ; Hawkes, J. ; Heinzelmann, G. ; Henri, G. ; Hermann, G. ; Hinton, J. A. ; Hofmann, W. ; Hoischen, Clemens ; Holch, T. L. ; Holler, M. ; Horns, D. ; Ivascenko, A. ; Iwasaki, H. ; Jacholkowska, A. ; Jamrozy, M. ; Janiak, M. ; Jankowsky, D. ; Jankowsky, F. ; Jingo, M. ; Jouvin, L. ; Jung-Richardt, I ; Kastendieck, M. A. ; Katarzynski, K. ; Katsuragawa, M. ; Katz, U. ; Kerszberg, D. ; Khangulyan, D. ; Khelifi, B. ; King, J. ; Klepser, S. ; Klochkov, D. ; Kluzniak, W. ; Komin, Nu ; Kosack, K. ; Krakau, S. ; Kraus, M. ; Krueger, P. P. ; Laffon, H. ; Lamanna, G. ; Lau, J. ; Lees, J-P ; Lefaucheur, J. ; Lemiere, A. ; Lemoine-Goumard, M. ; Lenain, J-P ; Leser, Eva ; Liu, R. ; Lohse, T. ; Lorentz, M. ; Lopez-Coto, R. ; Lypova, I ; Malyshev, D. ; Marandon, V ; Marcowith, A. ; Mariaud, C. ; Marx, R. ; Maurin, G. ; Maxted, N. ; Mayer, M. ; Meintjes, P. J. ; Meyer, M. ; Mitchell, A. M. W. ; Moderski, R. ; Mohamed, M. ; Mohrmann, L. ; Mora, K. ; Moulin, E. ; Murach, T. ; Nakashima, S. ; de Naurois, M. ; Ndiyavala, H. ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; Odaka, H. ; Ohm, S. ; Ostrowski, M. ; Oya, I ; Padovani, M. ; Panter, M. ; Parsons, R. D. ; Pekeur, N. W. ; Pelletier, G. ; Perennes, C. ; Petrucci, P-O ; Peyaud, B. ; Piel, Q. ; Pita, S. ; Poireau, V ; Poon, H. ; Prokhorov, D. ; Prokoph, H. ; Puelhofer, G. ; Punch, M. ; Quirrenbach, A. ; Raab, S. ; Rauth, R. ; Reimer, A. ; Reimer, O. ; Renaud, M. ; De Los Reyes, R. ; Rieger, F. ; Rinchiuso, L. ; Romoli, C. ; Rowell, G. ; Rudak, B. ; Rulten, C. B. ; Sahakian, V ; Saito, S. ; Sanchez, D. A. ; Santangelo, A. ; Sasaki, M. ; Schandri, M. ; Schlickeiser, R. ; Schussler, F. ; Schulz, A. ; Schwanke, U. ; Schwemmer, S. ; Seglar-Arroyo, M. ; Settimo, M. ; Seyffert, A. S. ; Shafi, N. ; Shilon, I ; Shiningayamwe, K. ; Simoni, R. ; Sol, H. ; Spanier, F. ; Spir-Jacob, M. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Steppa, Constantin Beverly ; Sushch, I ; Takahashi, T. ; Tavernet, J-P ; Tavernier, T. ; Taylor, A. M. ; Terrier, R. ; Tibaldo, L. ; Tiziani, D. ; Tluczykont, M. ; Trichard, C. ; Tsirou, M. ; Tsuji, N. ; Tuffs, R. ; Uchiyama, Y. ; van der Walt, J. ; van Eldik, C. ; van Rensburg, C. ; van Soelen, B. ; Vasileiadis, G. ; Veh, J. ; Venter, C. ; Viana, A. ; Vincent, P. ; Vink, J. ; Voisin, F. ; Voelk, H. J. ; Vuillaume, T. ; Wadiasingh, Z. ; Wagner, S. J. ; Wagner, P. ; Wagner, R. M. ; White, R. ; Wierzcholska, A. ; Willmann, P. ; Woernlein, A. ; Wouters, D. ; Yang, R. ; Zaborov, D. ; Zacharias, M. ; Zanin, R. ; Zdziarski, A. A. ; Zech, Alraune ; Zefi, F. ; Ziegler, A. ; Zorn, J. ; Zywucka, N.
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.
Abdalla, Hassan E. ; Abramowski, Attila ; Aharonian, Felix A. ; Benkhali, Faical Ait ; Akhperjanian, A. G. ; Andersson, T. ; Angüner, Ekrem Oǧuzhan ; Arrieta, M. ; Aubert, Pierre ; Backes, Michael ; Balzer, Arnim ; Barnard, Michelle ; Becherini, Yvonne ; Tjus, J. Becker ; Berge, David ; Bernhard, Sabrina ; Bernlöhr, K. ; Birsin, E. ; Blackwell, R. ; Boettcher, Markus ; Boisson, Catherine ; Bolmont, J. ; Bordas, Pol ; Bregeon, Johan ; Brun, Francois ; Brun, Pierre ; Bryan, Mark ; Bulik, Tomasz ; Capasso, M. ; Carr, John ; Casanova, Sabrina ; Chakraborty, N. ; Chalme-Calvet, R. ; Chaves, Ryan C. G. ; Chen, Andrew ; Chevalier, J. ; Chretien, M. ; Colafrancesco, Sergio ; Cologna, Gabriele ; Condon, B. ; Conrad, Jan ; Couturier, C. ; Cui, Y. ; Davids, I. D. ; Degrange, B. ; Deil, C. ; Devin, J. ; de Wilt, P. ; Djannati-Ataie, A. ; Domainko, W. ; Donath, A. ; Dubus, G. ; Dutson, K. ; Dyks, J. ; Dyrda, M. ; Edwards, T. ; Egberts, Kathrin ; Eger, P. ; Ernenwein, J. -P. ; Eschbach, S. ; Farnier, C. ; Fegan, S. ; Fernandes, M. V. ; Fiasson, A. ; Fontaine, G. ; Foerster, A. ; Funk, S. ; Fuessling, M. ; Gabici, S. ; Gajdus, M. ; Gallant, Y. A. ; Garrigoux, T. ; Giavitto, G. ; Giebels, B. ; Glicenstein, J. F. ; Gottschall, D. ; Goyal, A. ; Grondin, M. -H. ; Grudzinska, M. ; Hadasch, D. ; Hahn, J. ; Hawkes, J. ; Heinzelmann, G. ; Henri, G. ; Hermann, G. ; Hervet, O. ; Hillert, A. ; Hinton, James Anthony ; Hofmann, W. ; Hoischen, Clemens ; Holler, M. ; Horns, D. ; Ivascenko, A. ; Jacholkowska, A. ; Jamrozy, M. ; Janiak, M. ; Jankowsky, D. ; Jankowsky, F. ; Jingo, M. ; Jogler, T. ; Jouvin, L. ; Jung-Richardt, I. ; Kastendieck, M. A. ; Katarzynski, K. ; Katz, U. ; Kerszberg, D. ; Khelifi, B. ; Kieffer, M. ; King, J. ; Klepser, S. ; Klochkov, D. ; Kluzniak, W. ; Kolitzus, D. ; Komin, Nu. ; Kosack, K. ; Krakau, S. ; Kraus, M. ; Krayzel, F. ; Krueger, P. P. ; Laffon, H. ; Lamanna, G. ; Lau, J. ; Lees, J. -P. ; Lefaucheur, J. ; Lefranc, V. ; Lemiere, A. ; Lemoine-Goumard, M. ; Lenain, J. -P. ; Leser, Eva ; Liu, R. ; Lohse, T. ; Lorentz, M. ; Lypova, I. ; Marandon, V. ; Marcowith, A. ; Mariaud, C. ; Marx, R. ; Maurin, G. ; Maxted, N. ; Mayer, Michael ; Meintjes, P. J. ; Meyer, M. ; Mitchell, A. M. W. ; Moderski, R. ; Mohamed, M. ; Mora, K. ; Moulin, E. ; Murach, T. ; de Naurois, M. ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; Odaka, H. ; Ohm, S. ; Ostrowski, M. ; Oettl, S. ; Oya, I. ; Padovani, M. ; Panter, M. ; Parsons, R. D. ; Arribas, M. Paz ; Pekeur, N. W. ; Pelletier, G. ; Perennes, C. ; Petrucci, P. -O. ; Peyaud, B. ; Pita, S. ; Poon, H. ; Prokhorov, D. ; Prokoph, H. ; Puehlhofer, G. ; Punch, M. ; Quirrenbach, A. ; Raab, S. ; Reimer, A. ; Reimer, O. ; Renaud, M. ; Reyes, R. de los ; Rieger, F. ; Romoli, C. ; Rosier-Lees, S. ; Rowell, G. ; Rudak, B. ; Rulten, C. B. ; Sahakian, V. ; Salek, D. ; Sanchez, David M. ; Santangelo, A. ; Sasaki, M. ; Schlickeiser, R. ; Schuessler, F. ; Schulz, A. ; Schwanke, U. ; Schwemmer, S. ; Settimo, M. ; Seyffert, A. S. ; Shafi, N. ; Shilon, I. ; Simoni, R. ; Sol, H. ; Spanier, F. ; Spengler, G. ; Spies, F. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Stinzing, F. ; Stycz, K. ; Sushch, Iurii ; Tavernet, J. -P. ; Tavernier, T. ; Taylor, A. M. ; Terrier, R. ; Tibaldo, L. ; Tluczykont, M. ; Trichard, C. ; Tuffs, R. ; van der Walt, J. ; van Eldik, C. ; van Soelen, B. ; Vasileiadis, G. ; Veh, J. ; Venter, C. ; Viana, A. ; Vincent, P. ; Vink, J. ; Voisin, F. ; Voelk, H. J. ; Vuillaume, T. ; Wadiasingh, Z. ; Wagner, S. J. ; Wagner, P. ; Wagner, R. M. ; White, R. ; Wierzcholska, A. ; Willmann, P. ; Woernlein, A. ; Wouters, D. ; Yang, R. ; Zabalza, V. ; Zaborov, D. ; Zacharias, M. ; Zdziarski, A. A. ; Zech, Alraune ; Zefi, F. ; Ziegler, A. ; Zywucka, N.
A search for dark matter linelike signals iss performed in the vicinity of the Galactic Center by the H.E.S.S. experiment on observational data taken in 2014. An unbinned likelihood analysis iss developed to improve the sensitivity to linelike signals. The upgraded analysis along with newer data extend the energy coverage of the previous measurement down to 100 GeV. The 18 h of data collected with the H.E.S.S. array allow one to rule out at 95% C.L. the presence of a 130 GeV line (at l = -1.5 degrees, b = 0 degrees and for a dark matter profile centered at this location) previously reported in Fermi-LAT data. This new analysis overlaps significantly in energy with previous Fermi-LAT and H.E.S.S. results. No significant excess associated with dark matter annihilations was found in the energy range of 100 GeV to 2 TeV and upper limits on the gamma-ray flux and the velocity weighted annihilation cross section are derived adopting an Einasto dark matter halo profile. Expected limits for present and future large statistics H.E.S.S. observations are also given.
Abdalla, Hassan E. ; Abramowski, Attila ; Aharonian, Felix A. ; Benkhali, Faiçal Ait ; Akhperjanian, A. G. ; Angüner, Ekrem Oǧuzhan ; Arrieta, M. ; Aubert, Pierre ; Backes, Michael ; Balzer, Arnim ; Barnard, Michelle ; Becherini, Yvonne ; Tjus, Julia Becker ; Berge, David ; Bernhard, Sabrina ; Bernlöhr, K. ; Birsin, E. ; Blackwell, R. ; Bottcher, Markus ; Boisson, Catherine ; Bolmont, J. ; Bordas, Pol ; Bregeon, Johan ; Brun, Francois ; Brun, Pierre ; Bryan, Mark ; Bulik, Tomasz ; Capasso, M. ; Carr, John ; Casanova, Sabrina ; Chakraborty, N. ; Chalme-Calvet, R. ; Chaves, Ryan C. G. ; Chen, Andrew ; Chevalier, J. ; Chretien, M. ; Colafrancesco, Sergio ; Cologna, Gabriele ; Condon, B. ; Conrad, Jan ; Couturier, C. ; Cui, Y. ; Davids, I. D. ; Degrange, B. ; Deil, Christoph ; deWilt, P. ; Djannati-Atai, Arache ; Domainko, Wilfried ; Donath, Axel ; Dubus, Guillaume ; Dutson, Kate ; Dyks, J. ; Dyrda, M. ; Edwards, T. ; Egberts, Kathrin ; Eger, P. ; Ernenwein, J. -P. ; Eschbach, S. ; Farnier, C. ; Fegan, Stuart ; Fernandes, M. V. ; Fiasson, A. ; Fontaine, G. ; Foerster, A. ; Funk, S. ; Füßling, Matthias ; Gabici, Stefano ; Gajdus, M. ; Gallant, Y. A. ; Garrigoux, T. ; Giavitto, Gianluca ; Giebels, B. ; Glicenstein, J. F. ; Gottschall, Daniel ; Goyal, A. ; Grondin, M. -H. ; Grudzinska, M. ; Hadasch, Daniela ; Hahn, J. ; Hawkes, J. ; Heinzelmann, G. ; Henri, Gilles ; Hermann, G. ; Hervet, Olivier ; Hillert, A. ; Hinton, James Anthony ; Hofmann, Werner ; Hoischen, Clemens ; Holler, M. ; Horns, D. ; Ivascenko, Alex ; Jacholkowska, A. ; Jamrozy, Marek ; Janiak, M. ; Jankowsky, D. ; Jankowsky, Felix ; Jingo, M. ; Jogler, Tobias ; Jouvin, Lea ; Jung-Richardt, Ira ; Kastendieck, M. A. ; Katarzynski, Krzysztof ; Katz, Uli ; Kerszberg, D. ; Khelifi, B. ; Kieffer, M. ; King, J. ; Klepser, S. ; Klochkov, Dmitry ; Kluzniak, W. ; Kolitzus, D. ; Komin, Nu. ; Kosack, K. ; Krakau, S. ; Kraus, Michael ; Krayzel, F. ; Kruger, P. P. ; Laffon, H. ; Lamanna, G. ; Lau, Jeanie ; Lees, J. -P. ; Lefaucheur, J. ; Lefranc, V. ; Lemiere, A. ; Lemoine-Goumard, M. ; Lenain, J. -P. ; Leser, Eva ; Lohse, Thomas ; Lorentz, M. ; Lui, R. ; Lypova, Iryna ; Marandon, Vincent ; Marcowith, Alexandre ; Mariaud, C. ; Marx, R. ; Maurin, G. ; Maxted, N. ; Mayer, Michael ; Meintjes, Petrus Johannes ; Menzler, U. ; Meyer, Manuel ; Mitchell, A. M. W. ; Moderski, R. ; Mohamed, M. ; Mora, K. ; Moulin, E. ; Murach, T. ; de Naurois, Mathieu ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; Odaka, Hirokazu ; Ohm, Stefan ; Oettl, S. ; Ostrowski, M. ; Oya, I. ; Padovani, Marco ; Panter, M. ; Parsons, R. D. ; Arribas, M. Paz ; Pekeur, N. W. ; Pelletier, G. ; Petrucci, P. -O. ; Peyaud, B. ; Pita, S. ; Poon, Helen ; Prokhorov, Dmitry ; Prokoph, Heike ; Puehlhofer, Gerd ; Punch, Michael ; Quirrenbach, Andreas ; Raab, S. ; Reimer, Anita ; Reimer, Olaf ; Renaud, M. ; de los Reyes, R. ; Rieger, Frank ; Romoli, Carlo ; Rosier-Lees, S. ; Rowell, G. ; Rudak, B. ; Rulten, C. B. ; Sahakian, V. ; Salek, David ; Sanchez, David A. ; Santangelo, Andrea ; Sasaki, Manami ; Schlickeiser, Reinhard ; Schussler, F. ; Schulz, Andreas ; Schwanke, U. ; Schwemmer, S. ; Seyffert, A. S. ; Shafi, N. ; Simoni, R. ; Sol, H. ; Spanier, Felix ; Spengler, G. ; Spiess, F. ; Stawarz, Lukasz ; Steenkamp, R. ; Stegmann, Christian ; Stinzing, F. ; Stycz, K. ; Sushch, Iurii ; Tavernet, J. -P. ; Tavernier, T. ; Taylor, A. M. ; Terrier, R. ; Tluczykont, Martin ; Trichard, C. ; Tuffs, R. ; van der Walt, Johan ; van Eldik, Christopher ; van Soelen, Brian ; Vasileiadis, Georges ; Veh, J. ; Venter, C. ; Viana, A. ; Vincent, P. ; Vink, Jacco ; Voisin, F. ; Voelk, Heinrich J. ; Vuillaume, Thomas ; Wadiasingh, Z. ; Wagner, Stefan J. ; Wagner, P. ; Wagner, R. M. ; White, R. ; Wierzcholska, Alicja ; Willmann, P. ; Woernlein, A. ; Wouters, Denis ; Yang, R. ; Zabalza, Victor ; Zaborov, D. ; Zacharias, M. ; Zdziarski, A. A. ; Zech, Andreas ; Zefi, F. ; Ziegler, A. ; Zywucka, Natalia
The inner region of the Milky Way halo harbors a large amount of dark matter (DM). Given its proximity, it is one of the most promising targets to look for DM. We report on a search for the annihilations of DM particles using gamma-ray observations towards the inner 300 pc of the Milky Way, with the H.E.S.S. array of ground-based Cherenkov telescopes. The analysis is based on a 2D maximum likelihood method using Galactic Center (GC) data accumulated by H.E.S.S. over the last 10 years (2004-2014), and does not show any significant gamma-ray signal above background. Assuming Einasto and Navarro-Frenk-White DM density profiles at the GC, we derive upper limits on the annihilation cross section <sigma nu >. These constraints are the strongest obtained so far in the TeV DM mass range and improve upon previous limits by a factor 5. For the Einasto profile, the constraints reach <sigma nu > values of 6 x 10(-26) cm(3) s(-1) in the W+W- channel for a DM particle mass of 1.5 TeV, and 2 x 10(-26) cm(3) s(-1) in the tau(+)tau(-) channel for a 1 TeV mass. For the first time, ground-based gamma-ray observations have reached sufficient sensitivity to probe <sigma nu > values expected from the thermal relic density for TeV DM particles.
Abdalla, Hassan E. ; Adam, R. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Angüner, Ekrem Oǧuzhan ; Arakawa, M. ; Arcaro, C. ; Armand, C. ; Ashkar, H. ; Backes, M. ; Martins, V. Barbosa ; Barnard, M. ; Becherini, Y. ; Berge, D. ; Bernloehr, K. ; Bissaldi, E. ; Blackwell, R. ; Boettcher, M. ; Boisson, C. ; Bolmont, J. ; Bonnefoy, S. ; Bregeon, J. ; Breuhaus, M. ; Brun, F. ; Brun, P. ; Bryan, M. ; Buechele, M. ; Bulik, T. ; Bylund, T. ; Capasso, M. ; Caroff, S. ; Carosi, A. ; Casanova, Sabrina ; Cerruti, M. ; Chand, T. ; Chandra, S. ; Chen, A. ; Colafrancesco, S. ; Curylo, M. ; Davids, I. D. ; Deil, C. ; Devin, J. ; deWilt, P. ; Dirson, L. ; Djannati-Atai, A. ; Dmytriiev, A. ; Donath, A. ; Doroshenko, V ; Dyks, J. ; Egberts, Kathrin ; Emery, G. ; Ernenwein, J-P ; Eschbach, S. ; Feijen, K. ; Fegan, S. ; Fiasson, A. ; Fontaine, G. ; Funk, S. ; Fussling, Matthias ; Gabici, S. ; Gallant, Y. A. ; Gate, F. ; Giavitto, G. ; Giunti, L. ; Glawion, D. ; Glicenstein, J. F. ; Gottschall, D. ; Grondin, M-H ; Hahn, J. ; Haupt, M. ; Heinzelmann, G. ; Henri, G. ; Hermann, G. ; Hinton, J. A. ; Hofmann, W. ; Hoischen, Clemens ; Holch, T. L. ; Holler, M. ; Horns, D. ; Huber, D. ; Iwasaki, H. ; Jamrozy, M. ; Jankowsky, D. ; Jankowsky, F. ; Jardin-Blicq, A. ; Jung-Richardt, I ; Kastendieck, M. A. ; Katarzynski, K. ; Katsuragawa, M. ; Katz, U. ; Khangulyan, D. ; Khelifi, B. ; King, J. ; Klepser, S. ; Kluzniak, W. ; Komin, Nu ; Kosack, K. ; Kostunin, D. ; Kreter, M. ; Lamanna, G. ; Lemiere, A. ; Lemoine-Goumard, M. ; Lenain, J-P ; Leser, Eva ; Levy, C. ; Lohse, T. ; Lypova, I ; Mackey, J. ; Majumdar, J. ; Malyshev, D. ; Marandon, V ; Marcowith, A. ; Mares, A. ; Mariaud, C. ; Marti-Devesa, G. ; Marx, R. ; Maurin, G. ; Meintjes, P. J. ; Mitchell, A. M. W. ; Moderski, R. ; Mohamed, M. ; Mohrmann, L. ; Moore, C. ; Moulin, E. ; Muller, J. ; Murach, T. ; Nakashima, S. ; de Naurois, M. ; Ndiyavala, H. ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; Odaka, H. ; Ohm, S. ; Wilhelmi, E. de Ona ; Ostrowski, M. ; Oya, I ; Panter, M. ; Parsons, R. D. ; Perennes, C. ; Petrucci, P-O ; Peyaud, B. ; Piel, Q. ; Pita, S. ; Poireau, V ; Noel, A. Priyana ; Prokhorov, D. A. ; Prokoph, H. ; Puehlhofer, G. ; Punch, M. ; Quirrenbach, A. ; Raab, S. ; Rauth, R. ; Reimer, A. ; Reimer, O. ; Remy, Q. ; Renaud, M. ; Rieger, F. ; Rinchiuso, L. ; Romoli, C. ; Rowell, G. ; Rudak, B. ; Ruiz-Velasco, E. ; Sahakian, V ; Sailer, S. ; Saito, S. ; Sanchez, D. A. ; Santangelo, A. ; Sasaki, M. ; Schlickeiser, R. ; Schussler, F. ; Schulz, A. ; Schutte, H. M. ; Schwanke, U. ; Schwemmer, S. ; Seglar-Arroyo, M. ; Senniappan, M. ; Seyffert, A. S. ; Shafi, N. ; Shiningayamwe, K. ; Simoni, R. ; Sinha, A. ; Sol, H. ; Specovius, A. ; Spir-Jacob, M. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Steppa, Constantin Beverly ; Takahashi, T. ; Tavernier, T. ; Taylor, A. M. ; Terrier, R. ; Tiziani, D. ; Tluczykont, M. ; Trichard, C. ; Tsirou, M. ; Tsuji, N. ; Tuffs, R. ; Uchiyama, Y. ; van der Walt, D. J. ; van Eldik, C. ; van Rensburg, C. ; van Soelen, B. ; Vasileiadis, G. ; Veh, J. ; Venter, C. ; Vincent, P. ; Vink, J. ; Voelk, H. J. ; Vuillaume, T. ; Wadiasingh, Z. ; Wagner, S. J. ; White, R. ; Wierzcholska, A. ; Yang, R. ; Yoneda, H. ; Zacharias, M. ; Zanin, R. ; Zdziarski, A. A. ; Zech, Alraune ; Ziegler, A. ; Zorn, J. ; Zywucka, N. ; de Palma, F. ; Axelsson, M. ; Roberts, O. J.
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.
Abdalla, Hassan E. ; Adam, R. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Angüner, Ekrem Oǧuzhan ; Arakawa, M. ; Arcaro, C. ; Armand, C. ; Ashkar, H. ; Backes, M. ; Martins, V. Barbosa ; Barnard, M. ; Becherini, Y. ; Berge, D. ; Bernloehr, K. ; Blackwell, R. ; Böttcher, M. ; Boisson, C. ; Bolmont, J. ; Bonnefoy, S. ; Bregeon, J. ; Breuhaus, M. ; Brun, F. ; Brun, P. ; Bryan, M. ; Büchele, M. ; Bulik, T. ; Bylund, T. ; Capasso, M. ; Caroff, S. ; Carosi, A. ; Casanova, Sabrina ; Cerruti, M. ; Chand, T. ; Chandra, S. ; Chen, A. ; Colafrancesco, S. ; Curylo, M. ; Davids, I. D. ; Deil, C. ; Devin, J. ; DeWilt, P. ; Dirson, L. ; Djannati-Ata, A. ; Dmytriiev, A. ; Donath, A. ; Doroshenko, V ; Dyks, J. ; Egberts, Kathrin ; Emery, G. ; Ernenwein, J-P ; Eschbach, S. ; Feijen, K. ; Fegan, S. ; Fiasson, A. ; Fontaine, G. ; Funk, S. ; Füßling, Matthias ; Gabici, S. ; Gallant, Y. A. ; Gate, F. ; Giavitto, G. ; Glawion, D. ; Glicenstein, J. F. ; Gottschall, D. ; Grondin, M-H ; Hahn, J. ; Haupt, M. ; Heinzelmann, G. ; Henri, G. ; Hermann, G. ; Hinton, James Anthony ; Hofmann, W. ; Hoischen, Clemens ; Holch, Tim Lukas ; Holler, M. ; Horns, D. ; Huber, D. ; Iwasaki, H. ; Jamrozy, M. ; Jankowsky, D. ; Jankowsky, F. ; Jardin-Blicq, A. ; Jung-Richardt, I ; Kastendieck, M. A. ; Katarzynski, K. ; Katsuragawa, M. ; Katz, U. ; Khangulyan, D. ; Khelifi, B. ; King, J. ; Klepser, S. ; Kluzniak, W. ; Komin, Nu ; Kosack, K. ; Kostunin, D. ; Kraus, M. ; Lamanna, G. ; Lau, J. ; Lemiere, A. ; Lemoine-Goumard, M. ; Lenain, J-P ; Leser, Eva ; Levy, C. ; Lohse, T. ; Lypova, I ; Mackey, J. ; Majumdar, J. ; Malyshev, D. ; Marandon, V ; Marcowith, A. ; Mares, A. ; Mariaud, C. ; Marti-Devesa, G. ; Marx, R. ; Maurin, G. ; Meintjes, P. J. ; Mitchell, A. M. W. ; Moderski, R. ; Mohamed, M. ; Mohrmann, L. ; Moore, C. ; Moulin, E. ; Muller, J. ; Murach, T. ; Nakashima, S. ; de Naurois, M. ; Ndiyavala, H. ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; Odaka, H. ; Ohm, S. ; Wilhelmi, E. de Ona ; Ostrowski, M. ; Oya, I ; Panter, M. ; Parsons, R. D. ; Perennes, C. ; Petrucci, P-O ; Peyaud, B. ; Piel, Q. ; Pita, S. ; Poireau, V ; Priyana Noel, A. ; Prokhorov, D. A. ; Prokoph, H. ; Pühlhofer, G. ; Punch, M. ; Quirrenbach, A. ; Raab, S. ; Rauth, R. ; Reimer, A. ; Reimer, O. ; Remy, Q. ; Renaud, M. ; Rieger, F. ; Rinchiuso, L. ; Romoli, C. ; Rowell, G. ; Rudak, B. ; Ruiz-Velasco, E. ; Sahakian, V ; Saito, S. ; Sanchez, David M. ; Santangelo, A. ; Sasaki, M. ; Schlickeiser, R. ; Schüssler, F. ; Schulz, A. ; Schutte, H. ; Schwanke, U. ; Schwemmer, S. ; Seglar-Arroyo, M. ; Senniappan, M. ; Seyffert, A. S. ; Shafi, N. ; Shiningayamwe, K. ; Simoni, R. ; Sinha, A. ; Sol, H. ; Specovius, A. ; Spir-Jacob, M. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Steppa, Constantin Beverly ; Takahashi, T. ; Tavernier, T. ; Taylor, A. M. ; Terrier, R. ; Tiziani, D. ; Tluczykont, M. ; Trichard, C. ; Tsirou, M. ; Tsuji, N. ; Tuffs, R. ; Uchiyama, Y. ; van Der Walt, D. J. ; van Eldik, C. ; van Rensburg, C. ; van Soelen, B. ; Vasileiadis, G. ; Veh, J. ; Venter, C. ; Vincent, P. ; Vink, J. ; Voisin, F. ; Voelk, H. J. ; Vuillaume, T. ; Wadiasingh, Z. ; Wagner, S. J. ; White, R. ; Wierzcholska, A. ; Yang, R. ; Yoneda, H. ; Zacharias, Michael ; Zanin, R. ; Zdziarski, A. A. ; Zech, Alraune ; Ziegler, A. ; Zorn, J. ; Zywucka, N. ; Meyer, M.
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.
Abdalla, Hassan E. ; Adam, Remi ; Aharonian, Felix A. ; Benkhali, Faical Ait ; Angüner, Ekrem Oǧuzhan ; Arakawa, Masanori ; Arcaro, C ; Armand, Catherine ; Armstrong, T. ; Egberts, Kathrin
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.