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Sant'Ambrogio di Torino, Italy

Bulgarelli A.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Fioretti V.,CIFS Turin | Malaguti P.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Trifoglio M.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Gianotti F.,Istituto di Astrofisica Spaziale e Fisica Cosmica
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

BoGEMMS, (Bologna Geant4 Multi-Mission Simulator) is a software project for fast simulation of payload on board of scientific satellites for prompt background evaluation that has been developed at the INAF/IASF Bologna. By exploiting the Geant4 set of libraries, BoGEMMS allows to interactively set the geometrical and physical parameters (e.g. physics list, materials and thicknesses), recording the interactions (e.g. energy deposit, position, interacting particle) in NASA FITS and CERN root format output files and filtering the output as a real observation in space, to finally produce the background detected count rate and spectra. Four different types of output can be produced by the BoGEMMS capturing different aspects of the interactions. The simulator can also run in parallel jobs and store the results in a centralized server via xrootd protocol. The BoGEMMS is a multi-mission tool, generally designed to be applied to any high-energy mission for which the shielding and instruments performances analysis is required. © 2012 SPIE. Source


Cardillo M.,National institute for astrophysics | Cardillo M.,University of Rome Tor Vergata | Tavani M.,National institute for astrophysics | Tavani M.,University of Rome Tor Vergata | And 8 more authors.
Astronomy and Astrophysics | Year: 2014

The middle-aged supernova remnant (SNR) W44 has recently attracted attention because of its relevance regarding the origin of Galactic cosmic-rays. For the first time for a SNR, the gamma-ray missions AGILE and Fermi have established the spectral continuum below 200 MeV, which can be attributed to a neutral pion emission. Confirming the hadronic origin of the gamma-ray emission near 100 MeV is then of the greatest importance. Our paper is focused on a global re-assessment of all available data and models of particle acceleration in W44 with the goal of determining the hadronic and leptonic contributions to the overall spectrum on a firm ground. We also present new gamma-ray and CO NANTEN2 data on W44 and compare them to recently published AGILE and Fermi data. Our analysis strengthens previous studies and observations of the W44 complex environment and provides new information for more detailed modeling. In particular, we determine that the average gas density of the regions emitting 100 MeV-10 GeV gamma-rays is relatively high (n ~ 250-300 cm-3). The hadronic interpretation of the gamma-ray spectrum of W44 is viable and supported by strong evidence. It implies a relatively large value for the average magnetic field (B ≥ 102 μG) in the SNR surroundings, which is a sign of field amplification by shock-driven turbulence. Our new analysis establishes that the spectral index of the proton energy distribution function is p1 = 2.2 ± 0.1 at low energies and p2 = 3.2 ± 0.1 at high energies. We critically discuss hadronic versus leptonic-only models of emission taking radio and gamma-ray data into account simultaneously. We find that the leptonic models are disfavored by the combination of radio and gamma-ray data. Having determined the hadronic nature of the gamma-ray emission on firm ground, a number of theoretical challenges remain to be addressed. © ESO 2014. Source


Striani E.,University of Rome Tor Vergata | Tavani M.,University of Rome Tor Vergata | Tavani M.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Piano G.,Istituto di Astrofisica Spaziale e Fisica Cosmica | And 49 more authors.
Astrophysical Journal Letters | Year: 2011

We report on the extremely intense and fast gamma-ray flare above 100MeV detected by AGILE from the Crab Nebula in mid-April 2011. This event is the fourth of a sequence of reported major gamma-ray flares produced by the Crab Nebula in the period 2007/mid-2011. These events are attributed to strong radiative and plasma instabilities in the inner Crab Nebula, and their properties are crucial for theoretical studies of fast and efficient particle acceleration up to 1015 eV. Here we study the very rapid flux and spectral evolution of the event that on 2011 April 16 reached the record-high peak flux of F = (26 5) × 10-6 photons cm-2 s -1 with a rise-time timescale that we determine to be in the range 6-10hr. The peak flaring gamma-ray spectrum reaches a distinct maximum near 500MeV with no substantial emission above 1 GeV. The very rapid rise time and overall evolution of the Crab Nebula flare strongly constrain the acceleration mechanisms and challenge MHD models. We briefly discuss the theoretical implications of our observations. © 2011. The American Astronomical Society. All rights reserved. Source


Tavani M.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Tavani M.,University of Rome Tor Vergata | Giuliani A.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Chen A.W.,Istituto di Astrofisica Spaziale e Fisica Cosmica | And 63 more authors.
Astrophysical Journal Letters | Year: 2010

The supernova remnant (SNR) IC 443 is an intermediate-age remnant well known for its radio, optical, X-ray, and gamma-ray energy emissions. In this Letter, we study the gamma-ray emission above 100MeV from IC 443 as obtained by the AGILE satellite. A distinct pattern of diffuse emission in the energy range 100MeV-3GeV is detected across the SNR with its prominent maximum (source "A") localized in the northeastern shell with a flux F = (47±10) × 10?8 photons cm?2 s?1 above 100MeV. This location is the site of the strongest shock interaction between the SNR blast wave and the dense circumstellar medium. Source "A" is not coincident with the TeV source located 0.4° away and associated with a dense molecular cloud complex in the SNR central region. From our observations, and from the lack of detectable diffuse TeV emission from its northeastern rim, we demonstrate that electrons cannot be the main emitters of gamma rays in the range 0.1-10GeV at the site of the strongest SNR shock. The intensity, spectral characteristics, and location of the most prominent gamma-ray emission together with the absence of cospatial detectable TeV emission are consistent only with a hadronic model of cosmic-ray acceleration in the SNR. A high-density molecular cloud (cloud "E") provides a remarkable "target" for nucleonic interactions of accelerated hadrons; our results show enhanced gamma-ray production near the molecular cloud/shocked shell interaction site. IC 443 provides the first unambiguous evidence of cosmic-ray acceleration by SNRs. © 2010. The American Astronomical Society. All rights reserved. Source


Striani E.,University of Rome Tor Vergata | Vercellone S.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Tavani M.,University of Rome Tor Vergata | Tavani M.,Istituto di Astrofisica Spaziale e Fisica Cosmica | And 63 more authors.
Astrophysical Journal | Year: 2010

We present the gamma-ray data of the extraordinary flaring activity above 100 MeV from the flat spectrum radio quasar 3C 454.3 detected by AGILE during the month of 2009 December. 3C 454.3, which has been among the most active blazars of the FSRQ type since 2007, has been detected in the gamma-ray range with a progressively rising flux since 2009 November 10. The gamma-ray flux reached a value comparable with that of the Vela pulsar on 2009 December 2. Remarkably, between 2009 December 2 and 3, the source more than doubled its gamma-ray emission and became the brightest gamma-ray source in the sky with a peak flux of Fγ,p = (2000 ± 400) × 10-8ph cm-2 s-1 for a 1 day integration above 100 MeV. The gamma-ray intensity decreased in the following days with the source flux remaining at large values near Fγ ≃ (1000 ± 200) × 10-8 ph cm-2 s-1 for more than a week. This exceptional gamma-ray flare dissipated among the largest ever detected intrinsic radiated power in gamma-rays above 100 MeV (Lγ,source,peak ≃ 3 × 1046 erg s-1, for a relativistic Doppler factor of δ ≃ 30). The total isotropic irradiated energy of the month-long episode in the range 100 MeV-3 GeV is Eγ,iso ≃ 1056 erg. We report the intensity and spectral evolution of the gamma-ray emission across the flaring episode. We briefly discuss the important theoretical implications of our detection. © 2010. The American Astronomical Society. All rights reserved. Source

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