GRB3 - GRBs Observations vs. theory in the Swift era |
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Speaker |
Bianco, Carlo Luciano |
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Co-autors |
Maria Grazia Bernardini, Letizia Caito, Gustavo De Barros, Luca Izzo, Francesco Alessandro Massucci, Barbara Patricelli, Remo Ruffini |
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Talk Title |
The extended afterglow luminosity evolution over the equitemporal surfaces |
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Abstract |
Due to the ultrarelativistic velocity of the fireshell (Lorentz gamma factor 10^2 - 10^3), photons emitted at the same time in the laboratory frame (i.e. the one in which the center of the fireshell is at rest) from the fireshell surface but at different angles from the line of sight do not reach the observer at the same arrival time. Then, the signal we detect at a given value of the arrival time is a superposition of signals coming from different times in the laboratory frame. Therefore, they correspond to different values of the fireshell radius. Within the fireshell model, we trace back the beginning of the "plateau" phase in the GRB afterglow X-ray light curves to a collision between the decelerating front layer of the fireshell and a slower inner shell. It occurs at the end of the prompt emission phase. To determine the radius at which this collision occurs, and therefore the dynamics of the slower inner shell, it is fundamental to analyze the distribution of the extended afterglow bolometric luminosity over single EQTSs, in order to determine the radius from which it comes the most of the observed emission at any value of the arrival time. The computation will be separately performed over different selected EQTSs encompassing all the extended afterglow regimes, from the prompt emission all the way to the latest phases. The temporal evolution of the luminosity distribution over the EQTSs will be then presented, together with the corresponding temporal evolution of the EQTS apparent size in the sky. |
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