THE BRIGHTEST GAMMA-RAY FLARING BLAZAR IN THE SKY: <i>AGILE</i> AND MULTI-WAVELENGTH OBSERVATIONS OF 3C 454.3 DURING 2010 NOVEMBER

Abstract

Since 2005, the blazar 3C 454.3 has shown remarkable flaring activity at all\nfrequencies, and during the last four years it has exhibited more than one\ngamma-ray flare per year, becoming the most active gamma-ray blazar in the sky.\nWe present for the first time the multi-wavelength AGILE, SWIFT, INTEGRAL, and\nGASP-WEBT data collected in order to explain the extraordinary gamma-ray flare\nof 3C 454.3 which occurred in November 2010. On 2010 November 20 (MJD 55520),\n3C 454.3 reached a peak flux (E&gt;100 MeV) of F_gamma(p) = (6.8+-1.0)E-5 ph/cm2/s\non a time scale of about 12 hours, more than a factor of 6 higher than the flux\nof the brightest steady gamma-ray source, the Vela pulsar, and more than a\nfactor of 3 brighter than its previous super-flare on 2009 December 2-3. The\nmulti-wavelength data make a thorough study of the present event possible: the\ncomparison with the previous outbursts indicates a close similarity to the one\nthat occurred in 2009. By comparing the broadband emission before, during, and\nafter the gamma-ray flare, we find that the radio, optical and X-ray emission\nvaries within a factor 2-3, whereas the gamma-ray flux by a factor of 10. This\nremarkable behavior is modeled by an external Compton component driven by a\nsubstantial local enhancement of soft seed photons.\n