AGILE detection of a strong gamma-ray flare from the blazar 3C 454.3

TL;DR

The AGILE satellite detected the strongest gamma-ray flare from the blazar 3C 454.3, revealing significant variability and setting a record high flux level for this quasar among Flat Spectrum Radio Quasars.

Contribution

This is the first detection of 3C 454.3 by AGILE, providing new insights into its gamma-ray emission during a period of optical activity.

Findings

Detected gamma-ray emission at 13.8-sigma significance

Measured an average flux of (280 ± 40) x 10^-8 photons cm^-2 s^-1

Observed the highest gamma-ray flux ever from this quasar

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-$\sigma$ with an average flux (E$>$100 MeV) of $(280 \pm 40) \times 10^{-8}$ 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-$\sigma$ 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.