A4 Article in conference proceedings
The exceptional VHE gamma-ray outburst of PKS 1510-089 in May 2016

List of Authors: Michael Zacharias, Julian Sitarek, Dijana Dominis Prester, Felix Jankowsky, Elina Lindfors, Mahmoud Mohamed, David Sanchez, Tomislav Terzic
Publisher: Sissa Medialab Srl
Publication year: 2017
Journal: POS Proceedings of Science
Book title *: 35th International Cosmic Ray Conference, ICRC 2017
Journal name in source: Proceedings of Science
ISSN: 1824-8039


PKS 1510-089 (z=0.361) is one of only a handful of flat spectrum radio quasars that have been detected at very high energy (VHE, E > 100GeV) gamma rays. It is a very active source across the entire electromagnetic spectrum. VHE observations in May 2016 with H.E.S.S. and MAGIC revealed an exceptionally strong flare, which lasted for less than two nights, and exhibited a peak flux of about 0.8 times the flux of the Crab Nebula above 200GeV. The flare provides the first evidence of intranight variability at VHE in this source. While optical observations with ATOM reveal a counterpart at optical frequencies, Fermi-LAT observations reveal only low flux variability at high energy (HE, E > 100 MeV) gamma rays. Interestingly, the HE spectral index significantly hardens during the peak of the VHE flare, indicating a strong shift of the peak frequency of the high energy component. Given the expected strong absorption due to the broad-line region, the VHE emission region cannot be located deep within that region.

Internal Authors/Editors

Downloadable publication

This is an electronic reprint of the original article.
This reprint may differ from the original in pagination and typographic detail. Please cite the original version.

Last updated on 2019-21-08 at 19:56