Internal shocks as a candidate for Prompt Gamma Ray Bursts (GRB)s
Abstract
Internal shocks are one of the prominent dissipation mechanisms for prompt gamma-ray emission. In internal shocks, each collision between two shells forms a pair of forward and reverse shocks, which dissipate part of their kinetic energy into internal energy. The dissipation is governed by hydrodynamics. However, most studies in the literature treat this as a plastic collision of two infinitely thin shells without any reference to hydrodynamics. Starting from the basic properties of the central engine we derive the physical properties of the shells before and after their collision. The properties of the shocked regions are significantly different and imply interesting observable consequences such as different luminosities, peak times, and peak photon energies from these two shocked regions. In particular, we will show that the internal shock model can account for certain key features of the prompt gamma-ray spectra and the diversity of the light curves.