Bulk Compton Emission in the GRB Internal Shock Model

Abstract

We investigate the role of the bulk Compton-scattering process in the internal shock model. We numerically show that the radiation field created by internal shocks does not affect the efficiency of the energy conversion in the shocks even if fireball outflows have highly nonuniform velocity distributions. However, the bulk Compton-scattering produces an additional high energy component especially when variability in the outflows arises because of a modulation of the mass injected into a constant energy flow. We show that an isotropic energy of $10^{50-51}$ ergs could be radiated in the range of 100MeV-GeV through the scattering process, provided that the shell's Lorentz factor varies between 10 and $10^4$.

12 pages, 2 figures, 2 tables, accepted for publication in ApJL

References in corpus (5)

• Gamma-ray burst early optical afterglows: implications for the initial Lorentz factor and the central engine
• A Unified Treatment of the Gamma-Ray Burst 021211 and Its Afterglow Emissions
• On the Kinetic Energy and Radiative Efficiency of Gamma-Ray Bursts
• Optical Flash of GRB 990123: constraints on the physical parameter of the reverse shock
• GRBs Light Curves - Another Clue on the Inner Engine

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• Validation of Radiative Transfer Computation with Monte Carlo Method for Ultra-Relativistic Background Flow