On the Angular Resolution of the AGILE gamma-ray imaging detector
S. Sabatini, I. Donnarumma, M. Tavani, A. Trois, A. Bulgarelli, A. Argan, G. Barbiellini, P. W. Cattaneo, A. Chen, E. Del Monte, V. Fioretti, F. Gianotti, A. Gi… 展开作者
S. Sabatini, I. Donnarumma, M. Tavani, A. Trois, A. Bulgarelli, A. Argan, G. Barbiellini, P. W. Cattaneo, A. Chen, E. Del Monte, V. Fioretti, F. Gianotti, A. Giuliani, F. Longo, F. Lucarelli, A. Morselli, C. Pittori, F. Verrecchia, P. Caraveo
备注：
19 pages, 8 figures, accepted for publication in ApJ
We present a study of the Angular Resolution of the AGILE gamma-ray imaging detector (GRID) that is operational in space since April 2007. The AGILE instrument is made of an array of 12 planes each equipped with a Tungsten converter and Silicon micros trip detectors and is sensitive in the energy range 50 MeV - 10 GeV. Among the space instruments devoted to gamma-ray astrophysics, AGILE uniquely exploits an analog readout system with dedicated electronics coupled with Silicon detectors. We show the results of Monte Carlo simulations carried out to reproduce the gamma-ray detection by the GRID, and we compare them to in-flight data. We use the Crab (pulsar + Nebula) system for discussion of real data performance, since its E^{-2} energy spectrum is representative of the majority of gamma-ray sources. For Crab-like spectrum sources, the GRID angular resolution (FWHM of ~4deg at 100 MeV; ~0.8deg at 1 GeV; ~0.9deg integrating the full energy band from 100 MeV to tens of GeV) is stable across a large field of view, being characterized by a flat response up to 30deg off-axis. A comparison of the angular resolution obtained by the two operational gamma-ray instruments, AGILE-GRID and Fermi-LAT, is interesting in view of future gamma-ray missions, that are currently under study. The two instruments exploit different detector configurations affecting the angular resolution: the former being optimized in the readout and track reconstruction especially in the low-energy band, the latter in terms of converter thickness and power consumption. We show that, despite these differences, the angular resolution of both instruments is very similar between 100 MeV and a few GeV.
We give an overview of the AGILE gamma-ray satellite scientific highlights. AGILE is an Italian Space Agency (ASI) mission devoted to observations in the 30 MeV - 50 GeV gamma-ray energy range, with simultaneous X-ray imaging in the 18-60 keV band. Launched in April 2007, the AGILE satellite has completed its tenth year of operations in orbit, and it is substantially contributing to improve our knowledge of the high-energy sky. Emission from cosmic sources at energies above 100 MeV is intrinsically non-thermal, and the study of the wide variety of observed Galactic and extragalactic gamma-ray …
AGILE is a space mission launched in 2007 to study X-ray and gamma-ray astronomy. The AGILE team developed real-time analysis pipelines to detect transient phenomena such as Gamma-Ray Bursts (GRBs) and to react to external science alerts received by other facilities. The AGILE anti-coincidence system (ACS) comprises five panels (four lateral and one on the top) that surround the AGILE detectors to reject background charged particles. It can also detect hard X-ray photons in the energy range 50 - 200 KeV. The acquisition of the ACS data produces a time series for each panel. These time series c…
AGILE is one of the satellites currently detecting terrestrial gamma-ray flashes (TGFs). In particular, the AGILE Mini-CALorimeter detected more than 2000 events in 8 years activity, by exploiting a unique sub-millisecond timescale trigger logic and high-energy range. A change in the onboard configuration enhanced the trigger capabilities for the detection of these events, overcoming dead time issues and enlarging the detection rate of these events up to $>$50 TGFs/month, allowing to reveal shorter duration flashes. The quasi-equatorial low-inclination ( 2.5$^{\circ}$) orbit of AGILE allows fo…
High-energy gamma-ray activity from V404 Cygni detected by AGILE during the 2015 June outburst
AGILE卫星在2015年6月的射电、光学、X射线和软伽马射线频率观测到的爆发期间，探测到了来自X射线双星V404 Cygni的瞬态高能伽马射线发射。该活动由AGILE在50-400 MeV能带观测，时间为2015-06-24 UT 06：00：00至2015-06-26 UT 06：00：00（MJD 57197.25 - 57199.25），探测意义为${\sim}4.3σ$。伽马射线探测，与费米-LAT同期观测一致，与在无线电和硬X射线频率下观察到的明亮耀斑相关，并与511千电子伏线发射的强烈增强相关，可能表明轻子主导的瞬态喷流中的等离子体喷射。这个双星系统的AGILE观测与微类星体的情况是兼容的，在这种情况下，瞬态喷流是负责高能伽马射线发射。
We present a study on the gamma-ray emission detected by the AGILE-GRID from the region of the SNR G78.2+2.1 (Gamma Cygni). In order to investigate the possible presence of gamma rays associated with the SNR below 1 GeV, it is necessary to analyze the gamma-ray radiation underlying the strong emission from the pulsar PSR J2021+4026, which totally dominates the field. An "off-pulse" analysis has been carried out, by considering only the emission related to the pulsar off-pulse phase of the AGILE-GRID light curve. We found that the resulting off-pulsed emission in the region of the SNR - detecte…
The origin of cosmic neutrinos is still largely unknown. Using data obtained by the gamma-ray imager on board of the AGILE satellite, we systematically searched for transient gamma-ray sources above 100 MeV that are temporally and spatially coincident with ten recent high-energy neutrino IceCube events. We find three AGILE candidate sources that can be considered possible counterparts to neutrino events. Detecting 3 gamma-ray/neutrino associations out of 10 IceCube events is shown to be unlikely due to a chance coincidence. One of the sources is related to the BL Lac source TXS 0506+056. For t…
The follow-up of external science alerts received from Gamma-Ray Bursts (GRB) and Gravitational Waves (GW) detectors is one of the AGILE Team's current major activities. The AGILE team developed an automated real-time analysis pipeline to analyse AGILE Gamma-Ray Imaging Detector (GRID) data to detect possible counterparts in the energy range 0.1-10 GeV. This work presents a new approach for detecting GRBs using a Convolutional Neural Network (CNN) to classify the AGILE-GRID intensity maps improving the GRBs detection capability over the Li&Ma method, currently used by the AGILE team. The CNN i…
Diffuse galactic gamma-ray emission is produced by the interaction of cosmic rays (CRs) with the interstellar environment. The study of gamma-ray emission is therefore a powerful tool to investigate the origin of CRs and the processes through which they are accelerated. We aim to gain deeper insights of the nature of gamma-ray emission in the region of Orion, which is one of the best studied sites of on-going star formation, by analysing data from the AGILE satellite. The diffuse gamma-ray emission expected from the Orion region is relatively high. Its separation from the galactic plane also e…
The LIGO-Virgo Collaboration (LVC) detected, on 2017 August 17, an exceptional gravitational-wave (GW) event temporally consistent within $\sim\,1.7 \, \rm s$ with the GRB 1708117A observed by Fermi-GBM and INTEGRAL. The event turns out to be compatible with a neutron star-neutron star (NS-NS) coalescence that subsequently produced a radio/optical/X-ray transient detected at later times. We report the main results of the observations by the AGILE satellite of the GW170817 localization region (LR) and its electromagnetic (e.m.) counterpart. At the LVC detection time $T_0$, the GW170817 LR was o…
Aims. We present the second AGILE-GRID Catalog (2AGL) of γ-ray sources in the 100 MeV-10 GeV energy range. Methods. With respect to previous AGILE-GRID catalogs, the current 2AGL Catalog is based on the first 2.3 years of science data from the AGILE mission (the so called 'pointing mode') and incorporates more data and several analysis improvements, including better calibrations at the event reconstruction level, an updated model for the Galactic diffuse gamma-ray emission, a refined procedure for point-like source detection, and the inclusion of a search for extended γ-ray sources. Results. T…
AGILE is an ASI space mission launched in 2007 to study X-ray and gamma-ray phenomena in the energy range from $\sim20$ keV to $\sim10$ GeV. The AGILE Team developed a real-time analysis pipeline for the fast detection of transient sources, and the follow-up of external science alerts received through networks such as the General Coordinates Network. We developed a new Deep Learning method for detecting and localizing Gamma-Ray Bursts (GRB) in the AGILE/GRID sky maps. We trained the model using sky maps with GRBs simulated in a radius of 20 degrees from the center of the map, which is larger t…
Quantum Convolutional Neural Networks for the detection of Gamma-Ray Bursts in the AGILE space mission data
University of Bologna（博洛尼亚大学）；INAF/OAS Bologna（意大利国家天体物理研究所/博洛尼亚天体物理与空间科学天文台）；German Research Center for Artificial Intelligence (DFKI)（德国人工智能研究中心）；Università degli Studi di Modena e Reggio Emilia（摩德纳和雷焦艾米利亚大学）；Department of Physics and Astronomy, University of Bologna（博洛尼亚大学物理与天文学系）；INAF/OA Roma（意大利国家天体物理研究所/罗马天文台）；ASI/SSDC Roma（意大利航天局/罗马空间科学数据中心）；INAF/IAPS Roma（意大利国家天体物理研究所/罗马行星际与空间物理研究所）；INAF/IRA Bologna（意大利国家天体物理研究所/博洛尼亚射电天文研究所）；INAF/OA Catania（意大利国家天体物理研究所/卡塔尼亚天文台）；INAF/OA Trieste（意大利国家天体物理研究所/的里雅斯特天文台）
The polarimetry of gamma rays converting to an $e^+e^-$ pair would open a new window on the high-energy gamma-ray sky by, among other things, providing insight into the radiation mechanism in pulsars (curvature or synchrotron) or deciphering the composition of the gamma-ray emitting jets in blazars (leptonic or lepto-hadronic). The performance of polarimeters based on homogeneous active targets (gas detectors (MeV, HARPO) or emulsions (GeV, GRAINE) has been studied both with simulation and by the analysis of data collected with telescope prototypes on linearly-polarised gamma-ray beams, and fo…
The origin of the pulsed gamma-ray emission in pulsars remains an open issue. The combination of sensitive observations in the GeV domain by AGILE and {\em Fermi}-LAT and increasingly sophisticated numerical simulations have recently brought new insights into our understanding of the pulsed emission and particle acceleration processes in pulsars. Particle-in-cell simulations of pulsar magnetospheres show that the equatorial current sheet forming beyond the light cylinder is the main culprit for magnetic dissipation, particle acceleration and bright high-energy synchrotron radiation all togethe…
