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American Astronomical Society, Astrophysical Journal, 1(676), p. L13-L16, 2008

DOI: 10.1086/587170

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Agile Detection of a Strong Gamma-Ray Flare from the Blazar 3C 454.3

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Postprint: archiving forbidden
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Data provided by SHERPA/RoMEO

Abstract

We report the first blazar detection by the AGILE satellite. AGILE detected 3C 454.3 during a period of strongly enhanced optical emission in July 2007. AGILE observed the source with a dedicated repointing during the period 2007 July 24-30 with its two co-aligned imagers, the Gamma-Ray Imaging Detector and the hard X-ray imager Super-AGILE sensitive in the 30 MeV-50 GeV and 18-60 keV, respectively. Over the entire period, AGILE detected gamma-ray emission from 3C 454.3 at a significance level of 13.8-$σ$ with an average flux (E$>$100 MeV) of $(280 ± 40) \times 10^{-8}$ photons cm$^{-2}$ s$^{-1}$. The gamma-ray flux appears to be variable towards the end of the observation. No emission was detected by Super-AGILE in the energy range 20-60 keV, with a 3-$σ$ upper limit of $2.3 \times 10^{-3}$ photons cm$^{-2}$ s$^{-1}$. The gamma-ray flux level of 3C 454.3 detected by AGILE is the highest ever detected for this quasar and among the most intense gamma-ray fluxes ever detected from Flat Spectrum Radio Quasars. Comment: Accepted by Astrophysical Journal Letters; 14 pages, 3 EPS Figures, 1 Table