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AGILE is an ASI gamma-ray astrophysics space Mission which will operate in the 30 MeV - 50 GeV range with imaging capabilities also in the 10 - 40 keV range. Primary scientific goals include the study of AGNs, gamma-ray bursts, Galactic... more
AGILE is an ASI gamma-ray astrophysics space Mission which will operate in the 30 MeV - 50 GeV range with imaging capabilities also in the 10 - 40 keV range. Primary scientific goals include the study of AGNs, gamma-ray bursts, Galactic sources, unidentified gamma-ray sources, diffuse Galactic and extragalactic gamma-ray emission, high-precision timing studies, and Quantum Gravity testing. The AGILE
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The well-known Crab Nebula is at the center of the SN1054 supernova remnant. It consists of a rotationally powered pulsar interacting with a surrounding nebula through a relativistic particle wind. The emissions originating from the... more
The well-known Crab Nebula is at the center of the SN1054 supernova remnant. It consists of a rotationally powered pulsar interacting with a surrounding nebula through a relativistic particle wind. The emissions originating from the pulsar and nebula have been considered to be essentially stable. Here, we report the detection of strong gamma-ray (100 mega-electron volts to 10 giga-electron volts) flares observed by the AGILE satellite in September 2010 and October 2007. In both cases, the total gamma-ray flux increased by a factor of three compared with the non-flaring flux. The flare luminosity and short time scale favor an origin near the pulsar, and we discuss Chandra Observatory x-ray and Hubble Space Telescope optical follow-up observations of the nebula. Our observations challenge standard models of nebular emission and require power-law acceleration by shock-driven plasma wave turbulence within an approximately 1-day time scale.
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Research Interests: Physics and Astrophysics
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A fuzzy logic preprocessing is used in connection with a back propagation neural network in particle recognition. As application on 4 GeV CERN experimental and Monte Carlo data of e- and (pi) (superscript -, taken with the prototype of... more
A fuzzy logic preprocessing is used in connection with a back propagation neural network in particle recognition. As application on 4 GeV CERN experimental and Monte Carlo data of e- and (pi) (superscript -, taken with the prototype of the silicon Tungsten calorimeter of the Wizard collaboration, is shown. This preprocessing consists in giving as input to the net the membership value, for a given discriminating parameter value, to belong to a given particle class. In this way the input layer receives a normalized input. The net can then exploit the correlations between different parameters, resulting in an increased convergence speed and recognition capability of the net. Other advantages of this approach are its noise robustness and the simple generalization of other particle classes or energies.
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Research Interests: Dark Matter and Gamma Ray
GLAST, the next U.S. general gamma-ray astrophysics mission scheduled to be launched into low Earth orbit in April, 2006, for 5–10 years of operation, is described. A product of a NASA/DOE and international collaboration, the Large Area... more
GLAST, the next U.S. general gamma-ray astrophysics mission scheduled to be launched into low Earth orbit in April, 2006, for 5–10 years of operation, is described. A product of a NASA/DOE and international collaboration, the Large Area Telescope (LAT) is the primary instrument that covers the…
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The AGILE Satellite [8] [9], launched the 23rd April 2007, is an italian mission devoted to high energy gamma-ray astrophysics in the 30 MeV-50 GeV range, with a window in the hard-X domain 18-60 keV. One of the on-board detectors, the... more
The AGILE Satellite [8] [9], launched the 23rd April 2007, is an italian mission devoted to high energy gamma-ray astrophysics in the 30 MeV-50 GeV range, with a window in the hard-X domain 18-60 keV. One of the on-board detectors, the Mini-Calorimeter (MCAL), was also designed to work as all sky transient monitor in the energy range 0.33-100 MeV. Though
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... d, INFN Trieste, Padriciano 99, I-34012 Trieste, Italy. e, Dip. Fisica, Università di Trieste, via A. Valerio 2, I-34127 Trieste, Italy. f, INAF-IASF Milano, via E. Bassini 15, I-20133 Milano, Italy. g, INFN Roma 2, via della Ricerca... more
... d, INFN Trieste, Padriciano 99, I-34012 Trieste, Italy. e, Dip. Fisica, Università di Trieste, via A. Valerio 2, I-34127 Trieste, Italy. f, INAF-IASF Milano, via E. Bassini 15, I-20133 Milano, Italy. g, INFN Roma 2, via della Ricerca Scientifica 1, I-00133 Roma, Italy. ...
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ABSTRACT The Fermi Large Area Telescope (LAT) detected gamma-rays up to 4 GeV from two bright X-class solar flares on 2012 March 7, showing both an impulsive and temporally extended emission phases. The gamma-rays appear to originate from... more
ABSTRACT The Fermi Large Area Telescope (LAT) detected gamma-rays up to 4 GeV from two bright X-class solar flares on 2012 March 7, showing both an impulsive and temporally extended emission phases. The gamma-rays appear to originate from the same active region as the X-rays associated with these flares. The >100 MeV gamma-ray flux decreases monotonically during the first hour (impulsive phase) followed by a slower decrease for the next 20 hr. A power law with a high-energy exponential cutoff can adequately describe the photon spectrum. Assuming that the gamma rays result from the decay of pions produced by accelerated protons and ions with a power-law spectrum, we find that the index of that spectrum is ~3, with minor variations during the impulsive phase. During the extended phase the photon spectrum softens monotonically, requiring the proton index varying from ~4 to >5. The >30 MeV proton flux observed by the GOES satellites also shows a flux decrease and spectral softening, but with a harder spectrum (index ~2-3). Based on these observations, we explore the relative merits of prompt or continuous acceleration scenarios, hadronic or leptonic emission processes, and acceleration at the solar corona or by the fast coronal mass ejections. We conclude that the most likely scenario is continuous acceleration of protons in the solar corona that penetrate the lower solar atmosphere and produce pions that decay into gamma rays. However, acceleration in the downstream of the shock cannot be definitely ruled out.
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ABSTRACT The direct detection of annihilation products in cosmic rays offers an alternative way to search for supersymmetric dark matter particles candidates. The study of the spectrum of gamma-rays, antiprotons and positrons in space has... more
ABSTRACT The direct detection of annihilation products in cosmic rays offers an alternative way to search for supersymmetric dark matter particles candidates. The study of the spectrum of gamma-rays, antiprotons and positrons in space has already showed some deviation from the expected signals but with weak statistical evidence. We will review the present situation and the achievable limits with the experiments GLAST and PAMELA.
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Following the AGILE/GRID detection of the candidate gamma-ray transient AGL J1734-3310 (Bulgarelli et al., ATel #2017), whose position is consistent with the INTEGRAL unidentified source IGR J17354-3255 (Kuulkers et al., ATel #874), we... more
Following the AGILE/GRID detection of the candidate gamma-ray transient AGL J1734-3310 (Bulgarelli et al., ATel #2017), whose position is consistent with the INTEGRAL unidentified source IGR J17354-3255 (Kuulkers et al., ATel #874), we performed a Swift target of opportunity observation on the INTEGRAL source. The field was observed with Swift/XRT for 5.3 ks from 2009-04-17 01:08:59 to 2009-04-17 07:57:56 UT.
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Summary Searching for cosmic antiprotons, balloon-borne experiments were performed in the last years, but without a clear answer on the $$\bar p$$ rate and origin. Here we present the project of an antarctic flight of a balloonborne... more
Summary Searching for cosmic antiprotons, balloon-borne experiments were performed in the last years, but without a clear answer on the $$\bar p$$ rate and origin. Here we present the project of an antarctic flight of a balloonborne apparatus that in principle could be greatly helpful in clarifying the situation before that experiments on space station or satellites provide the high statistics