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
Creators: name: Collaboration, H. E. S. S.
name: Abdalla, H.
name: Adam, R.
name: Aharonian, F.
name: Benkhali, F. Ait
name: Angüner, E. O.
name: Arcaro, C.
name: Arm, C.
name: Armstrong, T.
name: Ashkar, H.
name: Backes, M.
name: Baghmanyan, V.
name: Martins, V. Barbosa
name: Barnacka, A.
name: Barnard, M.
name: Becherini, Y.
name: Berge, D.
name: Bernlöhr, K.
name: Bi, B.
name: Böttcher, M.
name: Boisson, C.
name: Bolmont, J.
name: Bonnefoy, S.
name: de Lavergne, M. de Bony
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: Caroff, S.
name: Carosi, A.
name: Casanova, S.
name: Ch, T.
name: Ch, S.
name: Chen, A.
name: Cotter, G.
name: Curyło, M.
name: Mbarubucyeye, J. Damascene
name: Davids, I. D.
name: Davies, J.
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: Dyks, J.
name: Egberts, K.
name: Eichhorn, F.
name: Einecke, S.
name: Emery, G.
name: Ernenwein, J. -P.
name: Feijen, K.
name: Fegan, S.
name: Fiasson, A.
name: de Clairfontaine, G. Fichet
name: Filipovic, M.
name: Fontaine, G.
name: Funk, S.
name: Füßling, M.
name: Gabici, S.
name: Gallant, Y. A.
name: Giavitto, G.
name: Giunti, L.
name: Glawion, D.
name: Glicenstein, J. F.
name: Gottschall, D.
name: Grondin, M. -H.
name: Hahn, J.
name: Haupt, M.
name: Hermann, G.
name: Hinton, J. A.
name: Hofmann, W.
name: Hoischen, C.
name: Holch, T. L.
name: Holler, M.
name: Hörbe, M.
name: Horns, D.
name: Huber, D.
name: Jamrozy, M.
name: Jankowsky, D.
name: Jankowsky, F.
name: Jardin-Blicq, A.
name: Joshi, V.
name: Jung-Richardt, I.
name: Kastendieck, M. A.
name: Katarzyński, K.
name: Katz, U.
name: Khangulyan, D.
name: Khélifi, B.
name: Klepser, S.
name: Kluźniak, W.
name: Komin, Nu.
name: Konno, R.
name: Kosack, K.
name: Kostunin, D.
name: Kreter, M.
name: Lamanna, G.
name: Lemière, A.
name: Lemoine-Goumard, M.
name: Lenain, J. -P.
name: Levy, C.
name: Lohse, T.
name: Lypova, I.
name: Mackey, J.
name: Majumdar, J.
name: Malyshev, D.
name: Malyshev, D.
name: Mar, V.
name: Marchegiani, P.
name: Marcowith, A.
name: Mares, A.
name: Martí-Devesa, G.
name: Marx, R.
name: Maurin, G.
name: Meintjes, P. J.
name: Meyer, M.
name: Mitchell, A. M. W.
name: Moderski, R.
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name: Moulin, E.
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name: de Naurois, M.
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name: Niemiec, J.
name: Oakes, L.
name: O'Brien, P.
name: Odaka, H.
name: Ohm, S.
name: Olivera-Nieto, L.
name: Wilhelmi, E. de Ona
name: Ostrowski, M.
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name: Romoli, C.
name: Rowell, G.
name: Rudak, B.
name: Ruiz-Velasco, E.
name: Sahakian, V.
name: Sailer, S.
name: Sanchez, D. A.
name: Santangelo, A.
name: Sasaki, M.
name: Scalici, M.
name: Schüssler, F.
name: Schutte, H. M.
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: Spencer, S.
name: Spir-Jacob, M.
name: Stawarz, Ł.
name: Sun, L.
name: Steenkamp, R.
name: Stegmann, C.
name: Steinmassl, S.
name: Steppa, C.
name: Takahashi, T.
name: Tavernier, T.
name: Taylor, A. M.
name: Terrier, R.
name: Tiziani, D.
name: Tluczykont, M.
name: Tomankova, L.
name: Trichard, C.
name: Tsirou, M.
name: Tuffs, R.
name: Uchiyama, Y.
name: van der Walt, D. J.
name: van Eldik, C.
name: van Rensburg, C.
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name: Vasileiadis, G.
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name: Wagner, S. J.
name: Watson, J.
name: Werner, F.
name: White, R.
name: Wierzcholska, A.
name: Wong, Yu Wun
name: Yusafzai, A.
name: Zacharias, M.
name: Zanin, R.
name: Zargaryan, D.
name: Zdziarski, A. A.
name: Zech, A.
name: Zhu, S. J.
name: Zorn, J.
name: Zouari, S.
name: Żywucka, N.
name: Collaboration, MAGIC
name: Acciari, V. A.
name: Ansoldi, S.
name: Antonelli, L. A.
name: Engels, A. Arbet
name: Asano, K.
name: Baack, D.
name: Babić, A.
name: Baquero, A.
name: de Almeida, U. Barres
name: Barrio, J. A.
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name: Saito, T.
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name: Satalecka, K.
name: Schleicher, B.
name: Schmidt, K.
name: Schweizer, T.
name: Sitarek, J.
name: Šnidarić, I.
name: Sobczynska, D.
name: Spolon, A.
name: Stamerra, A.
name: Strom, D.
name: Strzys, M.
name: Suda, Y.
name: Surić, T.
name: Takahashi, M.
name: Tavecchio, F.
name: Temnikov, P.
name: Terzić, T.
name: Teshima, M.
name: Torres-Albà, N.
name: Tosti, L.
name: Truzzi, S.
name: van Scherpenberg, J.
name: Vanzo, G.
name: Acosta, M. Vazquez
name: Ventura, S.
name: Verguilov, V.
name: Vigorito, C. F.
name: Vitale, V.
name: Vovk, I.
name: Will, M.
name: Zarić, D.
name: Jorstad, S. G.
name: Marscher, A. P.
name: Boccardi, B.
name: Casadio, C.
name: Hodgson, J.
name: Kim, J. -Y.
name: Krichbaum, T. P.
name: Lähteenmäki, A.
name: Tornikoski, M.
name: Traianou, E.
name: Weaver, Z. R.
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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, $E&gt;100\,$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 $\sim 20\,$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 ightcurve. Interestingly, a steep flux decrease is observed at the same time as the cessation of the VHE flare. In the high energy (HE, $E&gt;100\,$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 $\sim 50\,$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.
description: 25 pages, 17 figures. Accepted for publication by Astronomy &amp; Astrophysics. Corresponding authors: M. Zacharias, J. Sitarek, D. Sanchez, T. Terzic