出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We report the g -ray activity from the Intermediate BL Lac S5 0716+714 during 2007 September–
October observations by the AGILE satellite, coincident with a period of intense optical activity
of the source monitored by GASP–WEBT.
AGILE observed the source with its two co-aligned imagers, the Gamma-Ray Imaging Detector
(GRID) and the hard X-ray imager (Super-AGILE) sensitive in the energy range 30MeV–50 GeV
and 18–60 keV respectively, in two different periods: the first between 4 and 23 September 2007,
the second between 24 October and 1 November 2007.
Over the period 7–12 September, AGILE detected g -ray emission from the source at a significance
level of 9.6-s with an average flux (E>100MeV) of (97±15)×10−8 photons cm−2 s−1, increasing
by a factor of at least four within three days. No emission was detected by Super-AGILE in
the energy range 18–60 keV, with a 3-s upper limit of 10 mCrab in 335 ksec. The g -ray flux of
S5 0716+714 detected by AGILE is the highest ever detected for this blazar and one of the most
intense g -ray fluxes detected from a BL Lac object. The Spectral Energy Distribution (SED) of
mid-September seems to be consistent with the synchrotron self-Compton (SSC) emission model,
but only by including two SSC components with different variability.
In October 2007 AGILE repointed toward S5 0716+714 following an intense optical flare, measuring
an average flux of (47±11)×10−8 photons cm−2 s−1 at a significance level of 6.0-s .
The g -ray flux during both AGILE pointings appears to be highly variable on timescales of 1 day.
