Prompt-phase of GRBs: Implications from internal shocks

Internal shocks are one of the leading dissipation mechanisms for powering the prompt phase of Gamma-ray bursts (GRBs). The basic paradigm is that a central engine produces a variable outflow wherein the faster trailing material collides with the slower leading material at a distance from the engine. Each such collision produces a pair of shock fronts, viz., a reverse and a forward shock front propagating in the faster and the slower material, respectively. In general, the physical conditions in both the shocked regions are very different. In my talk, I will show how, starting from a few basic central engine parameters, a self-consistent hydrodynamic solution of both shocked regions provides ingredients for understanding the spectra and the light pulses of prompt-GRBs. I will also show how internal shocks in structured jets can possibly provide a unifying theme for classical GRBs (CGRBs), X-ray riches (XRRs) and  X-ray flashes (XRFs).