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- Del Monte, E., et al.
(author)
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The observation of GRBs with AGILE and the interesting cases of GRB 090618 and GRB 100724B
- 2011
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In: AIP Conf. Proc.. - : AIP. - 9780735409163 ; , s. 209-212
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Conference paper (peer-reviewed)abstract
- The AGILE satellite, in orbit since 2007, is localizing about 0.5 GRBs per month with the hard X-ray Imager superagile (18-60 keV) and is detecting around 1 GRB per week with the non-imaging Minicalorimeter (0.35 - 100 MeV). Up to now the AGILE Gamma Ray Imaging Detector firmly detected four GRBs in the energy band between 20 MeV and few GeV. In this presentation we review the status of the GRBs observation with AGILE, we discuss the upper limits in the gamma-ray band of the non-detected events and we show some interesting bursts, especially GRB 090618 (bright in soft and hard-X rays, optical and radio but lacking GeV emission) and GRB 100724B (with a bright GeV emission simultaneous to hard-X rays without delayed onset).
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2. |
- Pe’Er, A., et al.
(author)
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The Connection Between Thermal and Non-Thermal Emission in Gamma-ray Bursts : General considerations and GRB090902B as a Case Study
- 2011
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In: GAMMA RAY BURSTS 2010. American Institute of Physics Conference Series. - : AIP. - 9780735409163 ; , s. 91-94
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Conference paper (other academic/artistic)abstract
- Photospheric (thermal) emission is inherent to the gamma-ray burst (GRB) “fireball” model. We show that inclusion of this component in the analysis of the GRB prompt emission phase naturally explains some of the prompt GRB spectra seen by the Fermi satellite over its entire energy band. The sub-MeV peak is explained as multi-color black body emission, and the high energy tail, extending up to the GeV band, results from roughly similar contributions of synchrotron emission, synchrotron self Compton (SSC) and Comptonization of the thermal photons by energetic electrons originating after dissipation of the kinetic energy above the photosphere. We briefly discuss the theory of multicolor black body emission from relativistically expanding plasma, before showing how the analysis method proposed results in a complete, self consistent picture of the physical conditions at both emission sites of the thermal and non-thermal radiation. Furthermore, it enables to extract the values of the free model parameters. We demonstrate the analysis method on GRB090902B, and present the values of the physical parameters deduced. We briefly discuss the uniqueness of GRB090902B-type spectra.
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