TP-03

Radiative processes of GRBs

Marco Tavani (IFC-CNR)

We consider particle acceleration and radiative processes evolving from the first stage of radiation break-out (at a site closer to the central source) to a later phase merging with the GRB afterglows. Particle acceleration is required to be (maximally) efficient during the initial and afterglow phases. Synchrotron emission in its optically thin or partially suppressed modes is in very good agreement with GRB pulse spectral evolution. The optically thin shock synchrotron model (OTSSM) is also in agreement with the GRB afterglow emission. Hard X-ray spectra detected hours after the prompt emission of GRB 990123 and other bursts strongly indicate that particle re-acceleration occurs during very late stages of GRB evolution.