GRB4 - Models for GRBs |
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Speaker |
Bianco, Carlo Luciano |
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Co-autors |
Maria Grazia Bernardini, Letizia Caito, Gustavo De Barros, Luca Izzo, Barbara Patricelli, Remo Ruffini, Gregory, Vereshchagin, She-Sheng Xue |
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Talk Title |
The fireshell equations of motion |
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Abstract |
The Fireshell originating a Gamma-Ray Burst (GRB) encompasses an optically thick regime followed by an optically thin one. In the first one the fireshell self-accelerates from a Lorentz gamma factor equal to 1 all the way to 200-300. The physics of this system is based on the continuous annihilation of electron-positron pairs in an optically thick e+e- plasma with a small baryon loading. In the following regime, the optically thin fireshell, composed by the baryons left over after the transparency point, ballistically expands into the CircumBurst Medium (CBM). The kinematics and dynamics of the fireshell during both regimes will be analyzed, and a comparison with corresponding treatments in the current literature will be presented. Particular attention will be devoted to the analysis of the transparency point, since it represents both the final outcome of the optically thick regime and the initial condition of the optically thin one. Some consequences on the interpretation of the observed GRBs' light curves and spectra will be presented. In particular, it will be presented the possible identification of the proper GRB (P-GRB), the flash emitted when the fireshell becomes transparent, in the case of GRB 080916C, whose full details will be presented in a next talk by L. Izzo et al. In the present talk, in the optically thick regime the fireshell will be approximated, for simplicity, as an expanding shell with constant width in the laboratory frame, following Ruffini et al., A&A, 350, 334 (1999). Possible deviations from such an approximation will be discussed in a next talk by G. De Barros et al. |
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Talk view |
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