Not only once: the amazing gamma-ray activity of the blazar PKS 1510-089

Abstract

PKS 1510-089 is a powerful Flat Spectrum Radio Quasar at z=0.361 with radiative output dominated by the gamma-ray emission. In the last two years PKS 1510-089 showed high variability over all the electromagnetic spectrum and in particular very high gamma-ray activity was detected by the Gamma-Ray Imaging Detector on board the AGILE satellite with flaring episodes in August 2007 and March 2008. An extraordinary activity was detected in March 2009 with several flaring episodes and a flux that reached 500 x 10^{-8} photons cm^{-2} s^{-1}. Multiwavelength observations of PKS 1510-089 seem to indicate the presence of Seyfert-like features such as little blue bump and big blue bump. Moreover, X-ray observations suggested the presence of a soft X-ray excess that could be a feature of the bulk Comptonization mechanism. We present the results of the analysis of the multiwavelength data collected by GASP-WEBT, REM, Swift and AGILE during these gamma-ray flares and the theoretical implications for the emission mechanisms.