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Constraints on the emission region of 3C 279 during strong flares in 2014 and 2015 through VHE gamma-ray observations with HESS

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posted on 2019-09-10, 09:04 authored by H Abdalla, R Adam, F Aharonian, FA Benkhali, EO Anguner, M Arakawa, C Arcaro, C Armand, H Ashkar, M Backes, VB Martins, M Barnard, Y Becherini, D Berge, K Bernloehr, R Blackwell, M Bottcher, C Boisson, J Bolmont, S Bonnefoy, J Bregeon, M Breuhaus, F Brun, P Brun, M Bryan, M Buechele, T Bulik, T Bylund, M Capasso, S Caroff, A Carosi, S Casanova, M Cerruti, T Chand, S Chandra, A Chen, S Colafrancesco, M Curylo, ID Davids, C Deil, J Devin, P DeWilt, L Dirson, A Djannati-Ata, A Dmytriiev, A Donath, V Doroshenko, LO Drury, J Dyks, K Egberts, G Emery, J-P Ernenwein, S Eschbach, K Feijen, S Fegan, A Fiasson, G Fontaine, S Funk, M Fuessling, S Gabici, YA Gallant, F Gate, G Giavitto, D Glawion, JF Glicenstein, D Gottschall, M-H Grondin, J Hahn, M Haupt, G Heinzelmann, G Henri, G Hermann, JA Hinton, W Hofmann, C Hoischen, TL Holch, M Holler, D Horns, D Huber, H Iwasaki, M Jamrozy, D Jankowsky, F Jankowsky, A Jardin-Blicq, I Jung-Richardt, MA Kastendieck, K Katarzynski, M Katsuragawa, U Katz, D Khangulyan, B Khelifi, J King, S Klepser, W Kluzniak, N Komin, K Kosack, D Kostunin, M Kraus, G Lamanna, J Lau, A Lemiere, M Lemoine-Goumard, J-P Lenain, E Leser, C Levy, T Lohse, I Lypova, J Mackey, J Majumdar, D Malyshev, V Marandon, A Marcowith, A Mares, C Mariaud, G Marti-Devesa, R Marx, G Maurin, PJ Meintjes, AMW Mitchell, R Moderski, M Mohamed, L Mohrmann, C Moore, E Moulin, J Muller, T Murach, S Nakashima, M de Naurois, H Ndiyavala, F Niederwanger, J Niemiec, L Oakes, P O'Brien, H Odaka, S Ohm, EDO Wilhelmi, M Ostrowski, I Oya, M Panter, RD Parsons, C Perennes, P-O Petrucci, B Peyaud, Q Piel, S Pita, V Poireau, AP Noel, DA Prokhorov, H Prokoph, G Puehlhofer, M Punch, A Quirrenbach, S Raab, R Rauth, A Reimer, O Reimer, Q Remy, M Renaud, F Rieger, L Rinchiuso, C Romoli, G Rowell, B Rudak, E Ruiz-Velasco, V Sahakian, S Saito, DA Sanchez, A Santangelo, M Sasaki, R Schlickeiser, F Schussler, A Schulz, H Schutte, U Schwanke, S Schwemmer, M Seglar-Arroyo, M Senniappan, AS Seyffert, N Shafi, K Shiningayamwe, R Simoni, A Sinha, H Sol, A Specovius, M Spir-Jacob, L Stawarz, R Steenkamp, C Stegmann, C Steppa, T Takahashi, T Tavernier, AM Taylor, R Terrier, D Tiziani, M Tluczykont, C Trichard, M Tsirou, N Tsuji, R Tuffs, Y Uchiyama, DJ van Der Walt, C van Eldik, C van Rensburg, B van Soelen, G Vasileiadis, J Veh, C Venter, P Vincent, J Vink, F Voisin, HJ Voelk, T Vuillaume, Z Wadiasingh, SJ Wagner, R White, A Wierzcholska, R Yang, H Yoneda, M Zacharias, R Zanin, AA Zdziarski, A Zech, A Ziegler, J Zorn, N Zywucka, M Meyer
The flat spectrum radio quasar 3C 279 is known to exhibit pronounced variability in the high-energy (100 MeV <  E <  100 GeV) γ-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) γ-ray domain. While the observation in 2014 provides an upper limit, the observation in 2015 results in a signal with 8.7σ 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 ≳ 1.7 × 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.


The support of the Namibian authorities and of the University of Namibia in facilitating the construction and operation of H.E.S.S. is gratefully acknowledged, as is the support by the German Ministry for Education and Research (BMBF), the Max Planck Society, the German Research Foundation (DFG), the Helmholtz Association, the Alexander von Humboldt Foundation, the French Ministry of Higher Education, Research and Innovation, the Centre National de la Recherche Scientifique (CNRS/IN2P3 and CNRS/INSU), the Commissariat á l’énergie atomique et aux énergies alternatives (CEA), the U.K. Science and Technology Facilities Council (STFC), the Knut and Alice Wallenberg Foundation, the National Science Centre, Poland grant no. 2016/22/M/ST9/00382, the South African Department of Science and Technology and National Research Foundation, the University of Namibia, the National Commission on Research, Science & Technology of Namibia (NCRST), the Austrian Federal Ministry of Education, Science and Research and the Austrian Science Fund (FWF), the Australian Research Council (ARC), the Japan Society for the Promotion of Science and by the University of Amsterdam. We appreciate the excellent work of the technical support staff in Berlin, Zeuthen, Heidelberg, Palaiseau, Paris, Saclay, Tübingen and in Namibia in the construction and operation of the equipment. This work benefited from services provided by the H.E.S.S. Virtual Organisation, supported by the national resource providers of the EGI Federation. A.W. is supported by Polish National Agency for Academic Exchange (NAWA). This paper has made use of upto-date SMARTS optical/near-infrared lightcurves that are available at www. This research has made use of the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.



Astronomy and Astrophysics, 2019, 627, A159

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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