An updated list of AGILE brightγ-ray sources and their variability in pointing mode

Abstract

Aims. We present a variability study of a sample of bright γ-ray (30 Mev−50 Gev) sources. This sample is an extension of the first AGILE catalogue of γ-ray sources (1AGL), obtained using the complete set of AGILE observations in pointing mode performed during a 2.3 year period from July 9, 2007 until October 30, 2009. Methods. The dataset of AGILE pointed observations covers a long time interval and its γ-ray data archive is useful for monitoring studies of medium-to-high brightness γ-ray sources. In the analysis reported here, we used data obtained with an improved event filter that covers a wider field of view, on a much larger (about 27.5 months) dataset, integrating data on observation block time scales, which mostly range from a few days to thirty days. Results. The data processing resulted in a better characterized source list than 1AGL was, and includes 54 sources, 7 of which are new high galactic latitude (|BII| ≥ 5) sources, 8 are new sources on the galactic plane, and 20 sources from the previous catalogue with revised positions. Eight 1AGL sources (2 high-latitude and 6 on the galactic plane) were not detected in the final processing either because of low OB exposure and/or due to their position in complex galactic regions. We report the results in a catalogue of all the detections obtained in each single OB, including the variability results for each of these sources. In particular, we found that 12 sources out of 42 or 11 out of 53 are variable, depending on the variability index used, where 42 and 53 are the number of sources for which these indices could be calculated. Seven of the 11 variable sources are blazars, the others are Crab pulsar+nebula, LS I +61 • 303, Cyg X-3, and 1AGLR J2021+4030.

AGILE Detection of Gamma-Ray Sources Coincident with Cosmic Neutrino Events

“…upper limit on the gamma-ray emission above 100 MeV over an interval of 1 week just before T 0 . Similar cases of AGILE sources, both transients and steady, not confirmed by FERMI-LAT have been detected in the past (Pittori et al 2009;Verrecchia et al 2013;Bulgarelli et al 2018). Several reasons can explain these discrepancies: source variability; different spectral response of the instruments; source visibility/exposure due to the different observing modes; event classification algorithms; background model (especially important for sources near the Galactic plane).…”

Search of MeV–GeV counterparts of TeV sources with AGILE in pointing mode

“…The AGILE-GRID is sensitive in the energy range 30 MeV -50 GeV, and it consists of a silicon-tungsten tracker, a caesium iodide mini-calorimeter and an anticoincidence system made of segmented plastic scintillators. The use of the silicon strip technology allows to have good performance for the γ-ray GRID imager, approximately a small cube of ∼ 60 cm size, which achieves an effective area of the order of 500 cm 2 at several hundreds MeV, an angular resolution (at 68% containment radius) of about 4.3 • at 100 MeV, decreasing below 1 • for energies above 1 GeV (Chen et al 2013), an unprecedentedly large field of view (FOV) of about ∼ 2.5 sr, as well as accurate timing, positional and attitude information (source location accuracy 5 ′ -10 ′ for intense sources with S/N ∼ > 10).…”

Second AGILE catalogue of gamma-ray sources

“…This paper presents the 2AGL Catalog of high-energy γ-ray sources detected by the AGILE Gamma-Ray Imager Detector (GRID) in the energy range 100 MeV -10 GeV during the first 2.3 years of operations (2007)(2008)(2009) in the so called 'pointing mode'. This paper follows three previously published papers: the First AGILE-GRID Catalog of γ-ray sources (1AGL, Pittori et al 2009), the Catalog of variable γ-ray sources during the first 2.3 years of observations (1AGLR, Verrecchia et al 2013), and a Send offprint requests to: A.…”