The science of AGILE: part I Cocco, V.; Tavani, M.; Barbiellini, G. ...
Nuclear physics. Section B, Proceedings supplement,
12/2002, Letnik:
113, Številka:
1
Journal Article
AGILE is an ASI Small Scientific Mission dedicated to gamma-ray astrophysics, which will detect and image photons in the 30 MeV – 50 GeV and in the 10–40 keV energy ranges. It is planned to be ...operational in early 2004 and it will be the only Mission entirely dedicated to source detection above 30 MeV during the period 2004–2006. AGILE will be an excellent gamma-ray imager with a spatial resolution of ∼ 40 μm and a very large FOV (∼ 1/5 of the sky). It allows simultaneous observations in the hard X-ray and in the γ-ray bands and it is characterized by an optimal temporal resolution (absolute timing of ∼ 2 μs and deadtimes of ∼ 100 μs for the GRID and of ∼ 5 μs for Super-AGILE and the Mini-Calorimeter). AGILE main scientific objectives will be: Active Galactic Nuclei, Gamma-Ray Bursts, Pulsars, unidentified gamma-ray sources and diffuse Galactic and extragalactic gamma-ray emission. In this paper (Part I) we focus on the AGILE scientific goals, the AGILE instrument and the on-board data processing.
The study of γ rays is fundamental for our understanding of the universe: γ rays probe the most energetic phenomena occurring in nature, and several signatures of new physics are associated with the ...emission of γ rays. The main science objectives and the status of the new generation high-energy gamma-ray astrophysics experiment AGILE are presented.
The science of AGILE: part II Pittori, C.; Tavani, M.; Barbiellini, G. ...
Nuclear physics. Section B, Proceedings supplement,
12/2002, Letnik:
113, Številka:
1
Journal Article
In this paper (Part II) we discuss the expected scientific performance of the AGILE mission, focusing on the large FOV, the spatial resolution and PSF of the γ-ray imager, and the crucial capability ...of simultaneous hard-X and γ-ray imaging with ∼ 1 – 3 arcmin resolution.
AGILE, an Italian Space Agency (ASI) mission dedicated to the exploration of the gamma-ray Universe, was successfully launched on April 23, 2007 from the Indian base of Sriharikota in an low-particle ...background equatorial orbit at 550 km height. AGILE gamma ray range cover the 30 MeV - 50 GeV band with its detectors combined together in the Gamma-Ray Imaging Detector (GRID). An X-ray imager (SuperAGILE) operates in the 18 - 60 keV band. Some of the payload instruments are also operated to detect transient X and gamma events with the main target being the Gamma Ray Burst in the SuperAGILE band and above 300 keV. The GRID instrument consists of a Silicon-Tungsten Tracker, a Caesium Iodide Mini-Calorimeter (MCAL), and a plastic-scintillator Anticoincidence system (ACS). The GRID achieves an angular resolution of about 15' for bright sources with an unprecedented large field-of-view about 2.5 sr with a time resolution of few microsec and a very reduced dead-time (less than 200 microsec for a gamma detection). The hard X-ray imager (SuperAGILE) combines a tungsten coded mask with Si detector with a technology identical to the Si-Tracker. It is on top of the gamma-ray detector and has an optimal angular resolution (about 6 arcmin) with good sensitivity over about 1 sr field of view (10-15 mCrab on axis for a 1-day integration). The burst monitoring combines the data from SuperAGILE and from MCAL which operates independently with a specific operative mode from 300 keV up to several tens of MeV. All the detector operations are mastered by the Payload Data Handling Unit (PDHU) that includes several operation for data selection and background rejection. AGILE has very innovative scientific payload for what concern both its detectors and its operative mode. After more than one year of in orbit operation the in-flight performances of the instruments as well as the operation of the background reducing algorithm are presented and the main scientific results achieved are discussed.
We present a variability study of a sample of bright gamma-ray (30 MeV -- 50 GeV) sources. This sample is an extension of the first AGILE catalogue of gamma-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. The dataset of AGILE pointed observations covers a long time interval and its gamma-ray data archive is useful for monitoring studies of medium-to-high brightness gamma-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. 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{\deg}303, Cyg X-3, and 1AGLR J2021+4030.
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