arXiv subjects

M. Mastropietro

Publications and source records attributed to M. Mastropietro.

22 records · Page 2Linked to original sources

arXiv2008

AGILE detection of variable gamma-ray activity from the blazar S5 0716+714 in September-October 2007

We report the gamma-ray activity from the intermediate BL Lac S5 0716+714 during observations acquired by the AGILE satellite in September and October 2007. These detections of activity were contemporaneous with a period of intense optical activity, which was monitored by GASP-WEBT. This simultaneous optical and gamma-ray coverage allows us to study in detail the light curves, time lags, gamma-ray photon spectrum, and Spectral Energy Distributions (SEDs) during different states of activity. AGILE observed the source with its two co-aligned imagers, the Gamma-Ray Imaging Detector (GRID) and the hard X-ray imager (Super-AGILE), which are sensitive to the 30 MeV-50 GeV and 18-60 keV energy ranges, respectively. Observations were completed in two different periods, the first between 2007 September 4-23, and the second between 2007 October 24-November 1. Over the period 2007 September 7-12, AGILE detected gamma-ray emission from the source at a significance level of 9.6-sigma with an average flux (E>100 MeV) of (97 +/- 15) x 10^{-8} photons cm^{-2} s^{-1}, which increased by a factor of at least four within three days. No emission was detected by Super-AGILE for the energy range 18-60 keV to a 3-sigma upper limit of 10 mCrab in 335 ksec. In October 2007, AGILE repointed toward S5 0716+714 following an intense optical flare, measuring an average flux of (47 +/- 11) x 10^{-8} photons cm^{-2} s^{-1} at a significance level of 6.0-sigma. The gamma-ray flux of S5 0716+714 detected by AGILE is the highest ever detected for this blazar and one of the most intense gamma-ray fluxes detected from a BL Lac object. The SED of mid-September appears to be consistent with the synchrotron self-Compton (SSC) emission model, but only by including two SSC components of different variabilities.

astro-ph↗

arXiv2007

SuperAGILE: the hard X-ray Imager for the AGILE space mission

SuperAGILE is a coded mask experiment based on silicon microstrip detectors. It operates in the 15-45 keV nominal energy range, providing crossed one-dimensional images of the X-ray sky with an on-axis angular resolution of 6 arcmin, over a field of view in excess of 1 steradian. It was designed as the hard X-ray monitor of the AGILE space mission, a small satellite of the Italian Space Agency devoted to image the gamma-ray sky in the 30 MeV - 50 GeV energy band. The AGILE mission was launched in a low-earth orbit on 23^{rd} April 2007. In this paper we describe the SuperAGILE experiment, its construction and test processes, and its performance before flight, based on the on-ground test and calibrations.

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arXiv2006

Scientific performances of the XAA1.2 front-end chip for silicon microstrip detectors

The XAA1.2 is a custom ASIC chip for silicon microstrip detectors adapted by Ideas for the SuperAGILE instrument on board the AGILE space mission. The chip is equipped with 128 input channels, each one containing a charge preamplifier, shaper, peak detector and stretcher. The most important features of the ASIC are the extended linearity, low noise and low power consumption. The XAA1.2 underwent extensive laboratory testing in order to study its commandability and functionality and evaluate its scientific performances. In this paper we describe the XAA1.2 features, report the laboratory measurements and discuss the results emphasizing the scientific performances in the context of the SuperAGILE front-end electronics.

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arXiv2001

SuperAGILE: the X-ray Monitor of the AGILE gamma-ray Mission

SuperAGILE is the X-ray stage of the AGILE gamma-ray mission. It is devoted to monitor X-ray (10-40 keV) sources with a sensitivity better than 10 mCrabs in 50 ks and to detect X-ray transients in a field of view of 1.8 sr, well matched to that of the gamma-ray tracker, with few arc-minutes position resolution and better than 5 us timing resolution. SuperAGILE is designed to exploit one additional layer of four Si microstrip detectors placed on top of the AGILE tracker, and a system of four mutually orthogonal one-dimensional coded masks to encode the X-ray sky. The total geometric area is 1444 cm^2. Low noise electronics based on ASIC technology composes the front-end read out. We present here the instrumental and astrophysical performances of SuperAGILE as derived by analytical calculations, Monte Carlo simulations and experimental tests on a prototype of the silicon microstrip detector and front-end electronics.

astro-ph↗