FERMI GAMMA-RAY SPACE TELESCOPE OBSERVATIONS OF THE GAMMA-RAY OUTBURST FROM 3C454.3 IN NOVEMBER 2010

摘要

The flat-spectrum radio quasar 3C454.3 underwent an extraordinary 5 day γ -ray outburst in 2010 November when the daily flux measured with the Fermi Large Area Telescope (LAT) at photon energies E > 100 MeV reached (66 ± 2) × 10~(-6) photons cm~(-2) s~(-1). This is a factor of three higher than its previous maximum flux recorded in 2009 December and -5 times brighter than the Vela pulsar, which is normally the brightest source in the γ -ray sky. The 3 hr peak flux was (85 ± 5)×10~(-6) photons cm~(-2) s~(-1), corresponding to an apparent isotropic luminosity of (2.1 ± 0.2)×10~(50) erg s~(-1), the highest ever recorded for a blazar. In this Letter, we investigate the features of this exceptional event in the γ -ray band of the Fermi-LAT. In contrast to previous flares of the same source observed with the Fermi-LAT, clear spectral changes are observed during the flare.