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Abdalla, Hassan E. ; Collaboration, H. E. S. S. ; 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. 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, Alexandre ; 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, Emmanuel ; 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, Andrea ; 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.
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.
Extended VHE gamma-ray emission towards SGR1806-20, LBV 1806-20, and stellar cluster Cl*1806-20
(2018)
Abdalla, Hassan E. ; Abramowski, A. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Akhperjanian, A. G. ; Anguener, E. O. ; Arrieta, M. ; Aubert, P. ; Backes, M. ; Balzer, A. ; Barnard, M. ; Becherini, Y. ; Tjus, J. Becker ; Berge, D. ; Bernhard, S. ; Bernloehr, K. ; Birsin, E. ; 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 ; Chakraborty, N. ; Chalme-Calvet, R. ; Chaves, R. C. G. ; Chen, A. ; Chevalier, J. ; Chretien, M. ; Colafrancesco, S. ; Cologna, G. ; Condon, B. ; Conrad, J. ; Couturier, C. ; Cui, Y. ; Davids, I. D. ; Degrange, B. ; Deil, C. ; deWilt, P. ; 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. ; 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, 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, E. ; Lohse, T. ; Lorentz, M. ; Liu, R. ; Lypova, I. ; Marandon, V. ; Marcowith, Alexandre ; Mariaud, C. ; Marx, R. ; Maurin, G. ; Maxted, N. ; Mayer, M. ; Meintjes, P. J. ; Menzler, U. ; Meyer, M. ; Mitchell, A. M. W. ; Moderski, R. ; Mohamed, M. ; Mora, K. ; Moulin, Emmanuel ; Murach, T. ; de Naurois, M. ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; Odaka, H. ; Oettl, S. ; Ohm, S. ; Ostrowski, M. ; Oya, I. ; Padovani, M. ; Panter, M. ; Parsons, R. D. ; Arribas, M. Paz ; Pekeur, N. W. ; Pelletier, G. ; 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. ; de los Reyes, R. ; Rieger, F. ; Romoli, C. ; Rosier-Lees, S. ; Rowell, G. ; Rudak, B. ; Rulten, C. B. ; Sahakian, V. ; Salek, D. ; Sanchez, D. A. ; Santangelo, Andrea ; Sasaki, M. ; Schlickeiser, R. ; Schussler, F. ; Schulz, A. ; Schwanke, U. ; Schwemmer, S. ; 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. ; 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.
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.
First ground-based measurement of sub-20 GeV to 100 GeV gamma-Rays from the Vela pulsar with HESS II
(2018)
Abdalla, Hassan E. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Angüner, Ekrem Oǧuzhan ; Arakawa, M. ; Arcaro, C. ; Armand, C. ; Arrieta, M. ; Backes, M. ; Barnard, M. ; Becherini, Y. ; Tjus, J. Becker ; Berge, D. ; Bernhard, S. ; Bernlohr, 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. ; Bylund, T. ; Capasso, M. ; Caroff, S. ; Carosi, A. ; Casanova, Sabrina ; Cerruti, M. ; Chakraborty, N. ; Chandra, S. ; Chen, A. ; Colafrancesco, S. ; Condon, B. ; 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. ; Fegan, S. ; Fiasson, A. ; Fontaine, G. ; Funk, S. ; Fuessling, M. ; 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, J. A. ; Hofmann, W. ; Hoischen, Clemens ; Holch, T. L. ; Holler, M. ; Horns, D. ; Huber, D. ; Iwasaki, H. ; Jacholkowska, A. ; Jamrozy, M. ; Jankowsky, D. ; Jankowsky, F. ; Jouvin, L. ; Jung-Richardt, I ; Kastendieck, M. A. ; Katarzynski, K. ; Katsuragawa, M. ; Katz, U. ; Kerszberg, D. ; Khangulyan, D. ; Khelifi, B. ; King, J. ; Klepser, S. ; Kluzniak, W. ; Komin, Nu ; Kosack, K. ; Krakau, S. ; Kraus, M. ; Krüger, P. P. ; Lamanna, G. ; Lau, J. ; Lefaucheur, J. ; Lemiere, A. ; Lemoine-Goumard, M. ; Lenain, J-P ; Leser, Eva ; Lohse, T. ; Lorentz, M. ; Lopez-Coto, R. ; Lypova, I ; Malyshev, D. ; Marandon, V ; Marcowith, Alexandre ; Mariaud, C. ; Marti-Devesa, G. ; Marx, R. ; Maurin, G. ; Meintjes, P. J. ; Mitchell, A. M. W. ; Moderski, R. ; Mohamed, M. ; Mohrmann, L. ; Moulin, Emmanuel ; 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. ; 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. ; Renaud, M. ; Rieger, F. ; Rinchiuso, L. ; Romoli, C. ; Rowell, G. ; Rudak, B. ; Ruiz-Velasco, E. ; Sahakian, V ; Saito, S. ; Sanchez, D. A. ; Santangelo, Andrea ; Sasaki, M. ; Schlickeiser, R. ; Schussler, F. ; Schulz, A. ; Schwanke, U. ; Schwemmer, S. ; Seglar-Arroyo, M. ; Senniappan, M. ; Seyffert, A. S. ; Shafi, N. ; Shilon, I ; Shiningayamwe, K. ; Simoni, R. ; Sinha, A. ; Sol, H. ; Spanier, F. ; Specovius, A. ; Spir-Jacob, M. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Steppa, Constantin Beverly ; 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. ; Vincent, P. ; Vink, J. ; Voisin, F. ; Voelk, H. J. ; Vuillaume, T. ; Wadiasingh, Z. ; Wagner, S. J. ; Wagner, R. M. ; White, R. ; Wierzcholska, A. ; Yang, R. ; Zaborov, D. ; Zacharias, M. ; Zanin, R. ; Zdziarski, A. A. ; Zech, Alraune ; Zefi, F. ; Ziegler, A. ; Zorn, J. ; Zywucka, N. ; Kerr, M. ; Johnston, S. ; Shannon, R. M.
Aims. We report on the measurement and investigation of pulsed high-energy y-ray emission from the Vela pulsar, PSR B0833-45, based on observations with the largest telescope of H.E.S.S., CT5, in monoscopic mode, and on data obtained with the Fermi-LAT. Methods. Data from 40.3 h of observations carried out with the H.E.S.S. II array from 2013 to 2015 have been used. A dedicated very low-threshold event reconstruction and analysis pipeline was developed to achieve the lowest possible energy threshold. Eight years of Fermi-LAT data were analysed and also used as reference to validate the CT5 telescope response model and analysis methods. Results. A pulsed gamma-ray signal at a significance level of more than 15 sigma is detected from the P2 peak of the Vela pulsar light curve. Of a total of 15 835 events, more than 6000 lie at an energy below 20 GeV, implying a significant overlap between H.E.S.S. II-CT5 and the Fermi-LAT. While the investigation of the pulsar light curve with the LAT confirms characteristics previously known up to 20 GeV in the tens of GeV energy range, CT5 data show a change in the pulse morphology of P2, i.e. an extreme sharpening of its trailing edge, together with the possible onset of a new component at 3.4 sigma significance level. Assuming a power-law model for the P2 spectrum, an excellent agreement is found for the photon indices (Gamma similar or equal to 4.1) obtained with the two telescopes above 10 GeV and an upper bound of 8% is derived on the relative offset between their energy scales. Using data from both instruments, it is shown however that the spectrum of P2 in the 10-100 GeV has a pronounced curvature; this is a confirmation of the sub-exponential cut-off form found at lower energies with the LAT. This is further supported by weak evidence of an emission above 100 GeV obtained with CT5. In contrast, converging indications are found from both CT5 and LAT data for the emergence of a hard component above 50 GeV in the leading wing (LW2) of P2, which possibly extends beyond 100 GeV. Conclusions. The detection demonstrates the performance and understanding of CT5 from 100 GeV down to the sub-20 GeV domain, i.e. unprecedented low energy for ground-based gamma-ray astronomy. The extreme sharpening of the trailing edge of the P2 peak found in the H.E.S.S. II light curve of the Vela pulsar and the possible extension beyond 100 GeV of at least one of its features, LW2, provide further constraints to models of gamma-Ray emission from pulsars.
Abdalla, Hassan E. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Angüner, Ekrem Oǧuzhan ; Arakawa, M. ; Arcaro, C. ; Armand, C. ; Backes, M. ; Barnard, M. ; Becherini, Y. ; Berge, D. ; Bernloehr, K. ; Blackwell, R. ; Bottcher, M. ; Boisson, C. ; Bolmont, J. ; Bonnefoy, S. ; Bregeon, J. ; Brun, F. ; Brun, P. ; Bryan, M. ; Buechele, M. ; Bulik, T. ; Bylund, T. ; Capasso, M. ; Caroff, S. ; Carosi, A. ; Casanova, Sabrina ; Cerruti, M. ; Chakraborty, N. ; Chand, T. ; Chandra, S. ; Chaves, R. C. G. ; Chen, A. ; Colafrancesco, S. ; Condon, B. ; 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. ; Fuessling, M. ; 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. ; Jacholkowska, A. ; Jamrozy, M. ; Jankowsky, D. ; Jankowsky, F. ; Jouvin, L. ; 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 ; Lohse, T. ; Lopez-Coto, R. ; Lypova, I ; Malyshev, D. ; Marandon, V ; Marcowith, Alexandre ; Mariaud, C. ; Marti-Devesa, G. ; Marx, R. ; Maurin, G. ; Maxted, N. ; Meintjes, P. J. ; Mitchell, A. M. W. ; Moderski, R. ; Mohamed, M. ; Mohrmann, L. ; Moore, C. ; Moulin, Emmanuel ; 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. ; Renaud, M. ; Rieger, F. ; Rinchiuso, L. ; Romoli, C. ; Rowell, G. ; Rudak, B. ; Ruiz-Velasco, E. ; Sahakian, V ; Saito, S. ; Sanchez, David M. ; Santangelo, Andrea ; Sasaki, M. ; Schlickeiser, R. ; Schussler, F. ; Schulz, A. ; Schutte, H. ; Schwanke, U. ; Schwemmer, S. ; Seglar-Arroyo, M. ; Senniappan, M. ; Seyffert, A. S. ; Shafi, N. ; Shilon, I ; Shiningayamwe, K. ; Simoni, R. ; Sinha, A. ; Sol, H. ; Specovius, A. ; Spir-Jacob, M. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Steppa, Constantin Beverly ; Takahashi, T. ; Tavernet, J-P ; Tavernier, T. ; Taylor, A. M. ; Terrier, R. ; Tibaldo, Luigi ; 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. ; Zaborov, D. ; Zacharias, M. ; Zanin, R. ; Zdziarski, A. A. ; Zech, Alraune ; Ziegler, A. ; Zorn, J. ; Zywucka, N.
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.
Abdalla, Hassan E. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Angüner, Ekrem Oǧuzhan ; Arakawa, M. ; Arcaro, C. ; Armand, C. ; Arrieta, M. ; Backes, M. ; Barnard, M. ; Becherini, Y. ; Tjus, J. Becker ; Berge, D. ; Bernloehr, K. ; Blackwell, R. ; Bottcher, M. ; Boisson, C. ; Bolmont, J. ; Bonnefoy, S. ; Bordas, Pol ; Bregeon, J. ; Brun, F. ; Brun, P. ; Bryan, M. ; Buchele, M. ; Bulik, T. ; Bylund, T. ; Capasso, M. ; Caroff, S. ; Carosi, A. ; Casanova, Sabrina ; Cerruti, M. ; Chakraborty, N. ; Chand, T. ; Chandra, S. ; Chaves, R. C. G. ; Chen, A. ; Colafrancesco, S. ; Condon, B. ; 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. ; Fegan, S. ; Fiasson, A. ; Fontaine, G. ; Funk, S. ; Fuessling, M. ; 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. ; Jacholkowska, A. ; Jamrozy, M. ; Jankowsky, D. ; Jankowsky, F. ; Jouvin, L. ; 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. ; Kraus, M. ; Lamanna, G. ; Lau, J. ; Lefaucheur, J. ; Lemiere, A. ; Lemoine-Goumard, M. ; Lenain, J. -P. ; Leser, Eva ; Lohse, T. ; Lopez-Coto, R. ; Lorentz, M. ; Lypova, I. ; Malyshev, D. ; Marandon, V. ; Marcowith, Alexandre ; 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, Emmanuel ; Murach, T. ; Nakashima, S. ; de Naurois, M. ; Ndiyavala, H. ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; Odaka, H. ; Ohm, S. ; 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. ; Renaud, M. ; Rieger, F. ; Rinchiuso, L. ; Romoli, C. ; Rowell, G. ; Rudak, B. ; Ruiz-Velasco, E. ; Sahakian, V. ; Saito, S. ; Sanchez, David M. ; Santangelo, Andrea ; Sasaki, M. ; Schlickeiser, R. ; Schussler, F. ; Schulz, A. ; Schutte, H. ; Schwanke, U. ; Schwemmer, S. ; Seglar-Arroyo, M. ; Senniappan, M. ; Seyffert, A. S. ; Shafi, N. ; Shilon, I. ; Shiningayamwe, K. ; Simoni, R. ; Sinha, A. ; Sol, H. ; Specovius, A. ; Spir-Jacob, M. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Steppa, Constantin Beverly ; Takahashi, T. ; Tavernet, J. -P. ; 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. ; Wagner, R. M. ; White, R. ; Wierzcholska, A. ; Yang, R. ; Yoneda, H. ; Zaborov, D. ; Zacharias, M. ; Zanin, R. ; Zdziarski, A. A. ; Zech, Alraune ; Ziegler, A. ; Zorn, J. ; Zywucka, N.
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.
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, Alexandre ; 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, Emmanuel ; 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, Andrea ; 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, Alexandre ; 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, Emmanuel ; 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, Andrea ; 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, 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, Alexandre ; 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, Emmanuel ; 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, Andrea ; 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, A. ; Aharonian, Felix A. ; Benkhali, F. Ait ; Akhperjanian, A. G. ; Andersson, T. ; Anguener, E. O. ; Arrieta, M. ; Aubert, P. ; 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. ; 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. ; Dei, C. ; Devin, J. ; deWilt, P. ; Dirson, L. ; Djannati-Atai, A. ; Domainko, W. ; Donath, A. ; Dubus, G. ; Dutson, K. ; Dyks, J. ; Edwards, T. ; Egberts, Kathrin ; Eger, P. ; Ernenwein, J. -P. ; Eschbach, S. ; Farnier, C. ; Fegan, S. ; Fernandes, M. V. ; Fiasson, A. ; Fontaine, G. ; Foerster, A. ; Fukuyama, T. ; 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. ; 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. ; 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 ; Lohse, T. ; Lorentz, M. ; Liu, R. ; Lopez-Coto, R. ; Lypova, I. ; Marandon, V. ; Marcowith, Alexandre ; 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, Emmanuel ; Murach, T. ; de Naurois, M. ; Niederwanger, F. ; Niemiec, J. ; Oakes, L. ; Odaka, H. ; Oettl, 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. ; Puehlhofer, G. ; Punch, M. ; Quirrenbach, A. ; Raab, S. ; Reimer, A. ; Reimer, O. ; Renaud, M. ; de los Reyes, R. ; Rieger, F. ; Romoli, C. ; Rosier-Lees, S. ; Rowell, G. ; Rudak, B. ; Rulten, C. B. ; Sahakian, V. ; Salek, D. ; Sanchez, D. A. ; Santangelo, Andrea ; 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. ; Spanie, F. ; Spengler, G. ; Spies, F. ; Stawarz, L. ; Steenkamp, R. ; Stegmann, Christian ; Stinzing, F. ; Stycz, K. ; Sushch, I. ; Takahashi, T. ; 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 Edik, C. ; van Rensburg, C. ; van Soelen, B. ; Vasileiadis, G. ; Veh, J. ; Venter, C. ; Viana, A. ; Vincent, P. ; Vink, J. ; Voisin, F. ; Voelk, H. J. ; Volpe, F. ; 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.
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We report on the gamma-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) gamma-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 +/- 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 +/- 0.14, and the softest one is 2.51 +/- 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3 GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15-August 1) on Mrk 501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size less than or similar to 0.1 pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power (similar or equal to 10(44) erg s(-1)) constitutes only a small fraction (similar to 10(-3)) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20 GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude.