Multiwavelength observations of a VHE gamma-ray flare from PKS 1510−089 in 2015

¹ ETH Zurich, 8093 Zurich, Switzerland
² Università di Udine, and INFN Trieste, 33100 Udine, Italy
³ INAF National Institute for Astrophysics, 00136 Rome, Italy
⁴ Università di Padova and INFN, 35131 Padova, Italy
⁵ Croatian MAGIC Consortium, Rudjer Boskovic Institute, University of Rijeka, University of Split – FESB, University of Zagreb – FER, University of Osijek, Croatia
⁶ Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Salt Lake, Sector-1, 700064 Kolkata, India
⁷ Max-Planck-Institut für Physik, 80805 München, Germany
⁸ Universidad Complutense, 28040 Madrid, Spain
⁹ Inst. de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
¹⁰ Universidad de La Laguna, Dpto. Astrofísica, 38206 La Laguna, Tenerife, Spain
¹¹ University of Łódź, 90236 Lodz, Poland
¹² Deutsches Elektronen-Synchrotron (DESY), 15738 Zeuthen, Germany
¹³ Institut de Fisica d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology, Campus UAB, 08193 Bellaterra ( Barcelona), Spain
¹⁴ Università di Siena, and INFN Pisa, 53100 Siena, Italy
¹⁵ Universität Würzburg, 97074 Würzburg, Germany
¹⁶ Institute for Space Sciences (CSIC/IEEC), 08193 Barcelona, Spain
¹⁷ Technische Universität Dortmund, 44221 Dortmund, Germany
¹⁸ Finnish MAGIC Consortium, Tuorla Observatory, University of Turku and Astronomy Division, University of Oulu, Finland
¹⁹ Unitat de Física de les Radiacions, Departament de Física, and CERES-IEEC, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
²⁰ Universitat de Barcelona, ICC, IEEC-UB, 08028 Barcelona, Spain
²¹ Japanese MAGIC Consortium, ICRR, The University of Tokyo, Department of Physics and Hakubi Center, Kyoto University, Tokai University, The University of Tokushima, Japan
²² Inst. for Nucl. Research and Nucl. Energy, 1784 Sofia, Bulgaria
²³ Università di Pisa, and INFN Pisa, 56126 Pisa, Italy
²⁴ ICREA and Institute for Space Sciences (CSIC/IEEC), 08193 Barcelona, Spain
²⁵ Also at the Department of Physics of Kyoto University, Japan
²⁶ Now at Centro Brasileiro de Pesquisas Físicas (CBPF/MCTI), R. Dr. Xavier Sigaud, 150 – Urca, Rio de Janeiro – RJ, 22290-180, Brazil
²⁷ Now at NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA and Department of Physics and Department of Astronomy, University of Maryland, College Park, MD 20742, USA
²⁸ Humboldt University of Berlin, Institut für Physik Newtonstr. 15, 12489 Berlin, Germany
²⁹ Also at University of Trieste, Italy
³⁰ Now at École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland
³¹ Also at Japanese MAGIC Consortium, Japan
³² Now at Finnish Centre for Astronomy with ESO (FINCA), Turku, Finland
³³ Also at INAF-Triesteand Dept. of Physics & Astronomy, University of Bologna, 40126 Bologna, Italy
³⁴ Dip. di Fisica e Astronomia, Università di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
³⁵ INAF–Istituto di Radioastronomia, via Gobetti 101, 40129 Bologna, Italy
³⁶ KTH Royal Institute of Technology, Department of Physics, AlbaNova, 10691 Stockholm, Sweden
³⁷ Oskar Klein Centre for Cosmoparticle Physics, AlbaNova, 10691 Stockholm, Sweden
³⁸ INAF, Osservatorio Astrofisico di Torino, via Osservatorio 20, 10025 Pino Torinese, Italy
³⁹ Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Finland
⁴⁰ Aalto University Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
⁴¹ Aalto University Department of Radio Science and Engineering, PO Box 13000, 00076 AALTO, Finland
⁴² IAR, Boston University, 725 Commonwealth Ave, Boston, 02215, USA
⁴³ St. Petersburg State University, Universitetsky prospekt, 28, St. Petersburg 198504, Russia
⁴⁴ Physical Research Laboratory, Ahmedabad 380009, Gujrat, India
⁴⁵ Indian Institute of Technology, Gandhinagar 382355, Gujrat, India
⁴⁶ Department of Astronomy and Astrophysics, The Pennsylvania State University, 532-D, Davey Laboratory, University Park, PA 16802, USA
⁴⁷ Department of Physics, Lancaster University, Lancaster, LA1 4YW, UK
⁴⁸ Astrophysics Research Institute, Liverpool John Moores University, Brownlow Hill, Liverpool, L3 5RF, UK
⁴⁹ Pulkovo Observatory, St. Petersburg, Russia
⁵⁰ Crimean Astrophysical Observatory, Crimea

^⋆ Corresponding author: J. Sitarek, e-mail: jsitarek@uni.lodz.pl; J. Becerra González, e-mail: becerragonzalez@gmail.com; E. Lindfors, e-mail: elilin@utu.fi

Received: 25 October 2016
Accepted: 27 February 2017

Abstract

Context. PKS 1510−089 is one of only a few flat spectrum radio quasars detected in the very-high-energy (VHE, > 100 GeV) gamma-ray band.

Aims. We study the broadband spectral and temporal properties of the PKS 1510−089 emission during a high gamma-ray state.

Methods. We performed VHE gamma-ray observations of PKS 1510−089 with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes during a long, high gamma-ray state in May 2015. In order to perform broadband modeling of the source, we have also gathered contemporaneous multiwavelength data in radio, IR, optical photometry and polarization, UV, X-ray, and GeV gamma-ray ranges. We construct a broadband spectral energy distribution (SED) in two periods, selected according to VHE gamma-ray state.

Results. PKS 1510−089 was detected by MAGIC during a few day-long observations performed in the middle of a long, high optical and gamma-ray state, showing for the first time a significant VHE gamma-ray variability. Similarly to the optical and gamma-ray high state of the source detected in 2012, it was accompanied by a rotation of the optical polarization angle and the emission of a new jet component observed in radio. However, owing to large uncertainty on the knot separation time, the association with the VHE gamma-ray emission cannot be firmly established. The spectral shape in the VHE band during the flare is similar to those obtained during previous measurements of the source. The observed flux variability sets constraints for the first time on the size of the region from which VHE gamma rays are emitted. We model the broadband SED in the framework of the external Compton scenario and discuss the possible emission site in view of multiwavelength data and alternative emission models.