Observation of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 with H.E.S.S. and MAGIC in May 2016
Collaboration, H.E.S.S.; Abdalla, H.; Adam, R.; Aharonian, F.; Benkhali, F. Ait; Angüner, E.O.; Arcaro, C.; Arm, C.; Armstrong, T.; Ashkar, H.; Backes, M.; Baghmanyan, V.; Martins, V. Barbosa; Barnacka, A.; Barnard, M.; Becherini, Y.; Berge, D.; Bernlöhr, K.; Bi, B.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bonnefoy, S.; Lavergne, M. de Bony de; Bregeon, J.; Breuhaus, M.; Brun, F.; Brun, P.; Bryan, M.; Büchele, M.; Bulik, T.; Bylund, T.; Caroff, S.; Carosi, A.; Casanova, S.; Ch, T.; Ch, S.; Chen, A.; Cotter, G.; Curyło, M.; Mbarubucyeye, J. Damascene; Davids, I.D.; Davies, J.; Deil, C.; Devin, J.; deWilt, P.; Dirson, L.; Djannati-Ataï, A.; Dmytriiev, A.; Donath, A.; Doroshenko, V.; Dyks, J.; Egberts, K.; Eichhorn, F.; Einecke, S.; Emery, G.; Ernenwein, J.-P.; Feijen, K.; Fegan, S.; Fiasson, A.; Clairfontaine, G. Fichet de; Filipovic, M.; Fontaine, G.; Funk, S.; Füßling, M.; 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, C.; Holch, T.L.; Holler, M.; Hörbe, M.; Horns, D.; Huber, D.; Jamrozy, M.; Jankowsky, D.; Jankowsky, F.; Jardin-Blicq, A.; Joshi, V.; Jung-Richardt, I.; Kastendieck, M.A.; Katarzyński, K.; Katz, U.; Khangulyan, D.; Khélifi, B.; Klepser, S.; Kluźniak, W.; Komin, Nu; Konno, R.; Kosack, K.; Kostunin, D.; Kreter, M.; Lamanna, G.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Levy, C.; Lohse, T.; Lypova, I.; Mackey, J.; Majumdar, J.; Malyshev, D.; Malyshev, D.; Mar, V.; Marchegiani, P.; Marcowith, A.; Mares, A.; Martí-Devesa, G.; Marx, R.; Maurin, G.; Meintjes, P.J.; Meyer, M.; Mitchell, A.M.W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Montanari, A.; Moore, C.; Morris, P.; Moulin, E.; Muller, J.; Murach, T.; Nakashima, K.; Nayerhoda, A.; Naurois, M. de; Ndiyavala, H.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Ohm, S.; Olivera-Nieto, L.; Wilhelmi, E. de Ona; Ostrowski, M.; 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.; Pühlhofer, 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.; Schüssler, 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, Ł.; 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.; Walt, D.J. van der; Eldik, C. van; Rensburg, C. van; Soelen, B. van; Vasileiadis, G.; Veh, J.; Venter, C.; Vincent, P.; Vink, J.; Völk, 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, A.; Zhu, S.J.; Zorn, J.; Zouari, S.; Żywucka, N.; Collaboration, MAGIC; Acciari, V.A.; Ansoldi, S.; Antonelli, L.A.; Engels, A. Arbet; Asano, K.; Baack, D.; Babić, A.; Baquero, A.; Almeida, U. Barres de; Barrio, J.A.; González, J. Becerra; Bednarek, W.; Bellizzi, L.; Bernardini, E.; Berti, A.; Besenrieder, J.; Bhattacharyya, W.; Bigongiari, C.; Bil, A.; Blanch, O.; Bonnoli, G.; Bošnjak, Ž.; Busetto, G.; Carosi, R.; Ceribella, G.; Cerruti, M.; Chai, Y.; Chilingarian, A.; Cikota, S.; Colak, S.M.; Colin, U.; Colombo, E.; Contreras, J.L.; Cortina, J.; Covino, S.; D'Amico, G.; D'Elia, V.; Vela, P. Da; Dazzi, F.; Angelis, A. De; Lotto, B. De; Delfino, M.; Delgado, J.; Depaoli, D.; Pierro, F. Di; Venere, L. Di; Neira, E. Do Souto Espi; Prester, D. Dominis; Donini, A.; Dorner, D.; Doro, M.; Elsaesser, D.; Ramazani, V. Fallah; Fattorini, A.; Ferrara, G.; Foffano, L.; Fonseca, M.V.; Font, L.; Fruck, C.; Fukami, S.; López, R.J. García; Garczarczyk, M.; Gasparyan, S.; Gaug, M.; Giglietto, N.; Giordano, F.; Gliwny, P.; Godinović, N.; Green, D.; Hadasch, D.; Hahn, A.; Heckmann, L.; Herrera, J.; Hoang, J.; Hrupec, D.; Hütten, M.; Inada, T.; Inoue, S.; Ishio, K.; Iwamura, Y.; Jouvin, L.; Kajiwara, Y.; Karjalainen, M.; Kerszberg, D.; Kobayashi, Y.; Kubo, H.; Kushida, J.; Lamastra, A.; Lelas, D.; Leone, F.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Coto, R.; López-Oramas, A.; Loporchio, S..; Fraga, B Machado de Oliveira; Maggio, C.; Majumdar, P.; Makariev, M.; Mallamaci, M.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Mender, S.; Mićanović, S.; Miceli, D.; Miener, T.; Minev, M.; Mir, J.M.; Mirzoyan, R.; Molina, E.; Moralejo, A.; Morcuende, D.; Moreno, V.; Moretti, E.; Munar-Adrover, P.; Neustroev, V.; Nigro, C.; Nilsson, K.; Ninci, D.; Nishijima, K.; Noda, K.; Nozaki, S.; Ohtani, Y.; Oka, T.; Otero-Santos, J.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J.M.; Pavletić, L.; Nil, P. Pe; Perennes, C.; Persic, M.; Moroni, P.G. Prada; Pr, E.; Priyadarshi, C.; Puljak, I.; Rhode, W.; Ribó, M.; Rico, J.; Righi, C.; Rugliancich, A.; Saha, L.; Sahakyan, N.; Saito, T.; Sakurai, S.; Satalecka, K.; Schleicher, B.; Schmidt, K.; Schweizer, T.; Sitarek, J.; Šnidarić, I.; Sobczynska, D.; Spolon, A.; Stamerra, A.; Strom, D.; Strzys, M.; Suda, Y.; Surić, T.; Takahashi, M.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Teshima, M; Torres-Albà, N.; Tosti, L.; Truzzi, S.; Scherpenberg, J. van; Vanzo, G.; Acosta, M. Vazquez; Ventura, S.; Verguilov, V.; Vigorito, C.F.; Vitale, V.; Vovk, I.; Will, M.; Zarić, D.; Jorstad, S.G.; Marscher, Alan P.; Boccardi, B.; Casadio, C.; Hodgson, J.; Kim, J.-Y.; Krichbaum, T.P.; Lähteenmäki, A.; Tornikoski, M.; Traianou, E.; Weaver, Z.R.
The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behavior, and is one of only a few FSRQs detected at very high energy (VHE, E >100 GeV) 𝛾-rays. VHE 𝛾-ray observations with H.E.S.S. and MAGIC during late May and early June 2016 resulted in the detection of an unprecedented flare, which reveals for the first time VHE 𝛾-ray intranight variability in this source. While a common variability timescale of 1.5 hr is found, there is a significant deviation near the end of the flare with a timescale of ∼ 20 min marking the cessation of the event. The peak flux is nearly two orders of magnitude above the low-level emission. For the first time, curvature is detected in the VHE 𝛾-ray spectrum of PKS 1510-089, which is fully explained through absorption by the extragalactic background light. Optical R-band observations with ATOM reveal a counterpart of the 𝛾-ray flare, even though the detailed flux evolution differs from the VHE lightcurve. Interestingly, a steep flux decrease is observed at the same time as the cessation of the VHE flare. In the high energy (HE, E >100 MeV) 𝛾-ray band only a moderate flux increase is observed with Fermi-LAT, while the HE 𝛾-ray spectrum significantly hardens up to a photon index of 1.6. A search for broad-line region (BLR) absorption features in the 𝛾-ray spectrum indicates that the emission region is located outside of the BLR. Radio VLBI observations reveal a fast moving knot interacting with a standing jet feature around the time of the flare. As the standing feature is located ∼ 50 pc from the black hole, the emission region of the flare may have been located at a significant distance from the black hole. If this correlation is indeed true, VHE 𝛾 rays have been produced far down the jet where turbulent plasma crosses a standing shock.
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