GRB3 - GRBs Observations vs. theory in the Swift era |
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Speaker |
Bernardini, Maria Grazia |
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Co-autors |
C.L. Bianco, L. Caito, G. De Barros, L. Izzo, B. Patricelli, R. Ruffini. |
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Talk Title |
Collisions in the slowing down phase of the promt emission |
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Abstract |
The fireshell model provides an interpretation of the GRB structure as the joined contribution of the Proper-GRB (P-GRB) and of the afterglow emission, which consists of a rising part, a peak and a decaying phase. One of the purposes of the Swift mission is to observe the first few hours of the afterglow evolution, a largely unexplored window, and indeed it revealed a more complex behavior than expected. In particular the presence in most cases of a plateau advocated the presence of a late "energy inection" either from a late activity of the central engine or from the collision with slower material. The presence of this new component with respect to the "main" afterglow emission within the fireshell model has been interpreted as the result of a collision between the front layer of the fireshell and a slower tail of matter. The identification of this new component motivated a more quantitative study of its origin and characteristics. We investigated the kinematic of the collision in some specific GRBs that we already analysed within the fireshell model and we found a correlation between the expected Lorentz factor of the slower shell and the Lorentz factor of the fireshell at the transparency, calculated by the numerical modeling of the fireshell dynamics. This correlation reveals clues on the dynamics of the collision and on the matter distribution inside the fireshell at the transparency. |
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