Fermi/LAT detection of extraordinary variability in the gamma-ray emission of the blazar PKS 1510-089

Author： Foschini L. Bonnoli G. Ghisellini G. Tagliaferri G. Tavecchio F. Stamerra A.

E-ISSN： 1432-0746|555|issue|A138-A138

ISSN： 0004-6361

Source： Astronomy & Astrophysics, Vol.555, Iss.issue, 2013-07, pp. : A138-A138

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Abstract

We have reanalyzed the giant outburst of the blazar PKS 1510−089 (z = 0.36) that occurred on 2011 October−November. The γ-ray flux in the 0.1−100 GeV energy range exceeded the value of 10^-5 ph cm^-2 s^-1 for several days. The peak flux was reached on 2011 October 19, with a value of ~4.4 × 10^-5 ph cm^-2 s^-1, which in turn corresponds to a luminosity of ~2 × 10⁴⁹ erg s^-1. A very short timescale variability was measured. Particularly on 2011 October 18, the flux-doubling time was as short as ~20 min. This is the shortest variability ever detected in the MeV-GeV energy band. We compared our analysis with two other outbursts observed in 2009 March and 2012 February−March, when the blazar was also detected by H.E.S.S. and MAGIC to infer information about the emission at hundreds of GeV.