Since 2005 , the blazar 3CÂ 454.3 has shown remarkable flaring activity at all frequencies , and during the last four years it has exhibited more than one \gamma -ray flare per year , becoming the most active \gamma -ray blazar in the sky .
We present for the first time the multi-wavelength AGILE , Swift , INTEGRAL , and GASP-WEBT data collected in order to explain the extraordinary \gamma -ray flare of 3CÂ 454.3 which occurred in November 2010 .
On 2010 November 20 ( MJD 55520 ) , 3CÂ 454.3 reached a peak flux ( E > 100 MeV ) of F _ { \gamma } ^ { p } = ( 6.8 \pm 1.0 ) \times 10 ^ { -5 } photons cm ^ { -2 } s ^ { -1 } on a time scale of about 12 hours , more than a factor of 6 higher than the flux of the brightest steady \gamma -ray source , the Vela pulsar , and more than a factor of 3 brighter than its previous super-flare on 2009 December 2–3 .
The multi-wavelength data make a thorough study of the present event possible : the comparison with the previous outbursts indicates a close similarity to the one that occurred in 2009 .
By comparing the broadband emission before , during , and after the \gamma -ray flare , we find that the radio , optical and X-ray emission varies within a factor 2–3 , whereas the \gamma -ray flux by a factor of 10 .
This remarkable behavior is modeled by an external Compton component driven by a substantial local enhancement of soft seed photons .