Vercellone, S.S.VercelloneStriani, E.E.StrianiVittorini, V.V.VittoriniGiommi, PaoloPaoloGiommiLucarelli, FabrizioFabrizioLucarelliPittori, CarlottaCarlottaPittoriSantolamazza, P.P.SantolamazzaVerrecchia, FrancescoFrancescoVerrecchia2020-09-172020-09-172011-08-01https://hdl.handle.net/20.500.13025/2240The Astrophysical Journal Letters, Volume 736, Issue 2, article id. L38, <NUMPAGES>8</NUMPAGES> pp. (2011).Since 2005, the blazar 3C 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 3C 454.3 which occurred in 2010 November. On 2010 November 20 (MJD 55520), 3C 454.3 reached a peak flux (E >100 MeV) of F<SUP>p</SUP> <SUB>gamma</SUB> = (6.8 1.0) 10<SUP>-5</SUP> photons cm<SUP>-2</SUP> s<SUP>-1</SUP> on a timescale of about 12 hr, more than a factor of six higher than the flux of the brightest steady gamma-ray source, the Vela pulsar, and more than a factor of three brighter than its previous super-flare on 2009 December 2-3. The multi-wavelength data make possible a thorough study of the present event 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 of 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.galaxies activegalaxies jetsradiation mechanisms non-thermalquasars generalquasars individual 3C 454.310.1088/2041-8205/736/2/L38http://adsabs.harvard.edu/abs/2011ApJ...736L..38V2011ApJ...736L..38V