http://arxiv.org/abs/1511.02280
A prominent outburst of the flat spectrum radio quasar 3C~454.3 was observed in June 2014 with the Fermi Large Area Telescope. This outburst was characterized by a three-stage light-curve pattern—plateau, flare and post-flare—that occurred from 2014 May to July, in a similar pattern as observed during the exceptional outburst in 2010 November. The highest flux of the outburst reported in this paper occurred during 2014 June 7–29, showing a multiple-peak structure in the light-curves. The average flux in these 22 days was found to be $F[E > 100~\mathrm{MeV}] = (7.2 \pm 0.2) \times 10^{-6}~\mathrm{ph}~\mathrm{cm}^{-2}~\mathrm{s}^{-1}$, with a spectral index, for a simple power law, of $\Gamma = 2.05 \pm 0.01$. That made this outburst the first $\gamma$-ray high state of 3C~454.3 to be ever detected by {\em Fermi} with such a hard spectrum over several days. The highest flux was recorded on 2014 June 15, in a 3-hr bin, at MJD 56823.5625, at a level of $F[E > 100~\mathrm{MeV}] = (21.6 \pm 2.6) \times 10^{-6}~\mathrm{ph}~\mathrm{cm}^{-2}~\mathrm{s}^{-1}$. The rise time of one of the short subflares was found to be $T_r= 1000 \pm 500~$s at MJD=56827, when the flux increased from 4 to 12 $\times 10^{-6}~\mathrm{ph}~\mathrm{cm}^{-2}~\mathrm{s}^{-1}$. Several photons above 20 GeV were collected during this outburst, including one at 43 GeV on MJD 56827, constraining the $\gamma$-ray emission region to be located close to the outer boundary of the broad-line region (BLR), leading to fast flux variability.
R. Britto, S. Buson, B. Lott, et. al.
Tue, 10 Nov 15
58/62
Comments: Submitted to The Astrophysical Journal; 15 pages, 6 figures, 5 tables
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