The extraordinary gamma-ray flare of the blazar 3C 454.3
  We present the gamma-ray data of the extraordinary flaring activity above 100
MeV from the flat spectrum radio quasar 3C 454.3 detected by AGILE during the
month of December 2009. 3C 454.3, that has been among the most active blazars
of the FSRQ type since 2007, was detected in the gamma-ray range with a
progressively rising flux since November 10, 2009. The gamma-ray flux reached a
value comparable with that of the Vela pulsar on December 2, 2009. Remarkably,
between December 2 and 3, 2009 the source more than doubled its gamma-ray
emission and became the brightest gamma-ray source in the sky with a peak flux
of F_{\gamma,p} = (2000 \pm 400) x 10^-8 ph cm^-2 s^-1 for a 1-day integration
above 100 MeV. The gamma-ray intensity decreased in the following days with the
source flux remaining at large values near F \simeq (1000 \pm 200) x 10^-8 ph
cm^-2 s^-1 for more than a week. This exceptional gamma-ray flare dissipated
among the largest ever detected intrinsic radiated power in gamma-rays above
100 MeV (L_{\gamma, source, peak} \simeq 3 x 10^46 erg s^-1, for a relativistic
Doppler factor of {\delta} \simeq 30). The total isotropic irradiated energy of
the month-long episode in the range 100 MeV - 3 GeV is E_{\gamma,iso} \simeq
10^56 erg. We report the intensity and spectral evolution of the gamma-ray
emission across the flaring episode. We briefly discuss the important
theoretical implications of our detection.
