  Using a detailed model of the internal shock phase, we discuss the origin of
the prompt emission in gamma-ray bursts. We focus on the identification of the
dominant radiative process (Fermi-GBM range) and propose an explanation for
some features observed by Fermi-LAT at high energy in some GRB lightcurves.

High Energy Astrophysical Phenomena;Cosmology and Nongalactic Astrophysics