H.E.S.S. detection of very-high-energy gamma-ray emission from the quasar PKS 0736+017
Creators: name: Collaboration, H. E. S. S.
name: :
name: Abdalla, H.
name: Adam, R.
name: Aharonian, F.
name: Benkhali, F. Ait
name: Angüner, E. O.
name: Arakawa, M.
name: Arcaro, C.
name: Armand, C.
name: Ashkar, H.
name: Backes, M.
name: Martins, V. Barbosa
name: Barnard, M.
name: Becherini, Y.
name: Berge, D.
name: Bernlöhr, K.
name: Blackwell, R.
name: Böttcher, M.
name: Boisson, C.
name: Bolmont, J.
name: Bonnefoy, S.
name: Bregeon, J.
name: Breuhaus, M.
name: Brun, F.
name: Brun, P.
name: Bryan, M.
name: Büchele, M.
name: Bulik, T.
name: Bylund, T.
name: Capasso, M.
name: Caroff, S.
name: Carosi, A.
name: Casanova, S.
name: Cerruti, M.
name: Chand, T.
name: Chandra, S.
name: Chen, A.
name: Colafrancesco, S.
name: Curylo, M.
name: Davids, I. D.
name: Deil, C.
name: Devin, J.
name: deWilt, P.
name: Dirson, L.
name: Djannati-Ataï, A.
name: Dmytriiev, A.
name: Donath, A.
name: Doroshenko, V.
name: Drury, L. O'C.
name: Dyks, J.
name: Egberts, K.
name: Emery, G.
name: Ernenwein, J. -P.
name: Eschbach, S.
name: Feijen, K.
name: Fegan, S.
name: Fiasson, A.
name: Fontaine, G.
name: Funk, S.
name: Füßling, M.
name: Gabici, S.
name: Gallant, Y. A.
name: Gaté, F.
name: Giavitto, G.
name: Glawion, D.
name: Glicenstein, J. F.
name: Gottschall, D.
name: Grondin, M. -H.
name: Hahn, J.
name: Haupt, M.
name: Heinzelmann, G.
name: Henri, G.
name: Hermann, G.
name: Hinton, J. A.
name: Hofmann, W.
name: Hoischen, C.
name: Holch, T. L.
name: Holler, M.
name: Horns, D.
name: Huber, D.
name: Iwasaki, H.
name: Jamrozy, M.
name: Jankowsky, D.
name: Jankowsky, F.
name: Jardin-Blicq, A.
name: Jung-Richardt, I.
name: Kastendieck, M. A.
name: Katarzynski, K.
name: Katsuragawa, M.
name: Katz, U.
name: Khangulyan, D.
name: Khélifi, B.
name: King, J.
name: Klepser, S.
name: Kluzniak, W.
name: Komin, Nu.
name: Kosack, K.
name: Kostunin, D.
name: Kraus, M.
name: Lamanna, G.
name: Lau, J.
name: Lemière, A.
name: Lemoine-Goumard, M.
name: Lenain, J. -P.
name: Leser, E.
name: Levy, C.
name: Lohse, T.
name: Lypova, I.
name: Mackey, J.
name: Majumdar, J.
name: Malyshev, D.
name: Marandon, V.
name: Marcowith, A.
name: Mares, A.
name: Mariaud, C.
name: Martí-Devesa, G.
name: Marx, R.
name: Maurin, G.
name: Meintjes, P. J.
name: Mitchell, A. M. W.
name: Moderski, R.
name: Mohamed, M.
name: Mohrmann, L.
name: Muller, J.
name: Moore, C.
name: Moulin, E.
name: Murach, T.
name: Nakashima, S.
name: de Naurois, M.
name: Ndiyavala, H.
name: Niederwanger, F.
name: Niemiec, J.
name: Oakes, L.
name: O'Brien, P.
name: Odaka, H.
name: Ohm, S.
name: Wilhelmi, E. de Oña
name: Ostrowski, M.
name: Oya, I.
name: Panter, M.
name: Parsons, R. D.
name: Perennes, C.
name: Petrucci, P. -O.
name: Peyaud, B.
name: Piel, Q.
name: Pita, S.
name: Poireau, V.
name: Noel, A. Priyana
name: Prokhorov, D. A.
name: Prokoph, H.
name: Pühlhofer, G.
name: Punch, M.
name: Quirrenbach, A.
name: Raab, S.
name: Rauth, R.
name: Reimer, A.
name: Reimer, O.
name: Remy, Q.
name: Renaud, M.
name: Rieger, F.
name: Rinchiuso, L.
name: Romoli, C.
name: Rowell, G.
name: Rudak, B.
name: Ruiz-Velasco, E.
name: Sahakian, V.
name: Saito, S.
name: Sanchez, D. A.
name: Santangelo, A.
name: Sasaki, M.
name: Schlickeiser, R.
name: Schüssler, F.
name: Schulz, A.
name: Schutte, H.
name: Schwanke, U.
name: Schwemmer, S.
name: Seglar-Arroyo, M.
name: Senniappan, M.
name: Seyffert, A. S.
name: Shafi, N.
name: Shiningayamwe, K.
name: Simoni, R.
name: Sinha, A.
name: Sol, H.
name: Specovius, A.
name: Spir-Jacob, M.
name: Stawarz, L.
name: Steenkamp, R.
name: Stegmann, C.
name: Steppa, C.
name: Takahashi, T.
name: Tavernier, T.
name: Taylor, A. M.
name: Terrier, R.
name: Tiziani, D.
name: Tluczykont, M.
name: Trichard, C.
name: Tsirou, M.
name: Tsuji, N.
name: Tuffs, R.
name: Uchiyama, Y.
name: van der Walt, D. J.
name: van Eldik, C.
name: van Rensburg, C.
name: van Soelen, B.
name: Vasileiadis, G.
name: Veh, J.
name: Venter, C.
name: Vincent, P.
name: Vink, J.
name: Voisin, F.
name: Völk, H. J.
name: Vuillaume, T.
name: Wadiasingh, Z.
name: Wagner, S. J.
name: White, R.
name: Wierzcholska, A.
name: Yang, R.
name: Yoneda, H.
name: Zacharias, M.
name: Zanin, R.
name: Zdziarski, A. A.
name: Zech, A.
name: Ziegler, A.
name: Zorn, J.
name: Zywucka, N.
name: Smith, P. S.
Publisher: name: arXiv
Year: 2019
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Flat-spectrum radio-quasars (FSRQs) are rarely detected at very-high-energies (VHE; E&gt;100 GeV) due to their low-frequency-peaked SEDs. At present, only 6 FSRQs are known to emit VHE photons, representing only 7% of the VHE extragalactic catalog. Following the detection of MeV-GeV gamma-ray flaring activity from the FSRQ PKS 0736+017 (z=0.189) with Fermi, the H.E.S.S. array of Cherenkov telescopes triggered ToO observations on February 18, 2015, with the goal of studying the gamma-ray emission in the VHE band. 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-rays and optical/UV, and optical monitoring (photometry and spectro-polarimetry) by the Steward Observatory, the ATOM, the KAIT and the ASAS-SN telescope. VHE emission from PKS 0736+017 was detected with H.E.S.S. during the night of February 19, 2015, only. Fermi data indicate the presence of a gamma-ray flare, peaking at the time of the H.E.S.S. detection, with a flux doubling time-scale 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 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 with a bulk Lorentz factor $\simeq 20$, or at the level of the radius of the dusty torus with Gamma &gt; 60. PKS 0736+017 is the seventh FSRQ known to emit VHE photons and, at z=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.
description: In press in A&amp;A. 13 pages, 5 figures. Abstract abridged