학술논문
HESS detection of very high-energy gamma-ray emission from the quasar PKS 0736+017
Document Type
Author
Abdalla, H.; Adam, R.; Aharonian, F.; Benkhali, F. Ait; Anguner, E. O.; Arakawa, M.; Arcaro, C.; Armand, C.; Ashkar, H.; Backes, M.; Martins, V. Barbosa; Barnard, M.; Becherini, Yvonne; Berge, D.; Bernloehr, K.; Blackwell, R.; Bottcher, M.; Boisson, C.; Bolmont, J.; Bonnefoy, S.; Bregeon, J.; Breuhaus, M.; Brun, F.; Brun, P.; Bryan, M.; Buechele, M.; Bulik, T.; Bylund, Tomas; Capasso, M.; Caroff, S.; Carosi, A.; Casanova, S.; Cenuti, 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; Drury, L. O ' C; Dyks, J.; Egberts, K.; 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, J. A.; Hofmann, W.; Hoischen, C.; 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.; Kraus, M.; Lamanna, G.; Lau, J.; Lemiere, A.; Lemoine-Goumard, M.; Lenain, J-P; Leser, E.; 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.; Muller, J.; Moore, C.; Moulin, E.; Murach, T.; Nakashima, S.; de Naurois, M.; Ndiyavala, H.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; 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.; Puehlhofer, G.; Punch, Michael; 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, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schuessler, F.; Schulz, A.; Schutte, H.; Schwanke, U.; Schwemmer, S.; Seglar-Arroyo, M.; Senniappan, Mohanraj; Seyffert, A. S.; Shafi, N.; Shiningayamwe, K.; Simoni, R.; Sinha, A.; Sol, H.; Specovius, A.; Spir-Jacob, M.; Stawarz, L.; Steenkamp, R.; Stegmann, C.; Steppa, C.; 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, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Ziegler, A.; Zorn, J.; Zywucka, N. N.; Smith, P. S.
Source
Astronomy and Astrophysics. 633:1-11
Subject
Language
English
ISSN
0004-6361
1432-0746
1432-0746
Abstract
Context. Flat-spectrum radio-quasars (FSRQs) are rarely detected at very high energies (E& x2004;>=& x2004;100 GeV) due to their low-frequency-peaked spectral energy distributions. At present, only six FSRQs are known to emit very high-energy (VHE) photons, representing only 7% of the VHE extragalactic catalog, which is largely dominated by high-frequency-peaked BL Lacertae objects. Aims. Following the detection of MeV-GeV gamma-ray flaring activity from the FSRQ PKS 0736+017 (z& x2004;=& x2004;0.189) with Fermi-LAT, the H.E.S.S. array of Cherenkov telescopes triggered target-of-opportunity (ToO) observations on February 18, 2015, with the goal of studying the gamma-ray emission in the VHE band. Methods. H.E.S.S. ToO observations were carried out during the nights of February 18, 19, 21, and 24, 2015. Together with Fermi-LAT, the multi-wavelength coverage of the flare includes Swift observations in soft X-ray and optical-UV bands, and optical monitoring (photometry and spectro-polarimetry) by the Steward Observatory, and the ATOM, the KAIT, and the ASAS-SN telescopes. Results. VHE emission from PKS 0736+017 was detected with H.E.S.S. only during the night of February 19, 2015. Fermi-LAT data indicate the presence of a gamma-ray flare, peaking at the time of the H.E.S.S. detection, with a flux doubling timescale of around six hours. The gamma-ray flare was accompanied by at least a 1 mag brightening of the non-thermal optical continuum. No simultaneous observations at longer wavelengths are available for the night of the H.E.S.S. detection. The gamma-ray observations with H.E.S.S. and Fermi-LAT are used to put constraints on the location of the gamma-ray emitting region during the flare: it is constrained to be just outside the radius of the broad-line region r(BLR) with a bulk Lorentz factor Gamma& x2004;similar or equal to& x2004;20, or at the level of the radius of the dusty torus r(torus) with Gamma& x2004;similar or equal to& x2004;60. Conclusions. PKS 0736+017 is the seventh FSRQ known to emit VHE photons, and at z& x2004;=& x2004;0.189 is the nearest so far. The location of the gamma-ray emitting region during the flare can be tightly constrained thanks to opacity, variability, and collimation arguments.