Naslov
H.E.S.S. and MAGIC observations of a sudden cessation of a very-high-energy γ-ray flare in PKS 1510−089 in May 2016

Autori
H.E.S.S. Collaboration ; Abdalla, H. ; ... ; Żywucka, N. ; MAGIC Collaboration ; Acciari, V. A. ; ... ; Babić, Ana ; ... ; Bošnjak, Željka ; ... ; Cikota, Stefan ; ... ; Dominis Prester, Dijana ; ... ; Godinović, Nikola ; ... ; Hrupec, Dario ; ... ; Lelas, Damir ; ... ; Manganaro, Marina ; ... ; Mićanović, Saša ; ... ; Pavletić, Lovro ; ... ; Puljak, Ivica ; ... ; Šnidarić, Iva ; ... ; Surić, Tihomir ; ... ; Terzić, Tomislav ; ... ; Zarić, Darko ; ... ; Weaver, Z.R.

Kolaboracija
H.E.S.S. Collaboration ; MAGIC Collaboration

Izvornik
Astronomy & astrophysics (Berlin) (0004-6361) 648 (2021); A23, 22

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
radiation mechanisms: non-thermal / quasars: individual: PKS 1510−089 / galaxies: active / relativistic processes

Sažetak
The flat spectrum radio quasar (FSRQ) PKS 1510−089 is known for its complex multiwavelength behaviour and it is one of only a few FSRQs detected in very-high-energy (VHE, E > 100 GeV) γ rays. The VHE γ-ray observations with H.E.S.S. and MAGIC in late May and early June 2016 resulted in the detection of an unprecedented flare, which revealed, for the first time, VHE γ-ray intranight variability for this source. While a common variability timescale of 1.5 h has been 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, a curvature was detected in the VHE γ-ray spectrum of PKS 1510–089, which can be fully explained by the absorption on the part of the extragalactic background light. Optical R-band observations with ATOM revealed a counterpart of the γ-ray flare, even though the detailed flux evolution differs from the VHE γ-ray light curve. Interestingly, a steep flux decrease was observed at the same time as the cessation of the VHE γ-ray flare. In the high-energy (HE, E > 100 MeV) γ-ray band, only a moderate flux increase was 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 very-long-baseline interferometry 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 is indeed a true correlation, the VHE γ rays must have been produced far down in the jet, where turbulent plasma crosses a standing shock.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

POVEZANOST RADA