Electron acceleration in relativistic GRB shocks
Abstract
The shock model of gamma-ray bursts (GRBs) contains two equipartition parameters: the magnetic energy density and the kinetic energy density of the electrons relative to the total energy density of the shock, "epsilon_B" and "epsilon_e", respectively. These are free parameters within the model. Whereas the Weibel shock theory and numerical simulations fix "epsilon_B" at the level of ~few times(10^{-3}...10^{-4}), no understanding of "epsilon_e" exists so far. Here we demonstrate that it inevitably follows from the theory that "epsilon_e"~(epsilon_B)^(1/2). The GRB afteglow data fully agree with this theoretical prediction. Our result explains why the electrons are close to equipartition in GRBs. The "epsilon_e"-"epsilon_B" relation can potentially be used to reduce the number of free parameters in afterglow models.
Cite
@article{arxiv.astro-ph/0609347,
title = {Electron acceleration in relativistic GRB shocks},
author = {Mikhail V. Medvedev},
journal= {arXiv preprint arXiv:astro-ph/0609347},
year = {2011}
}
Comments
4 pages, 2 figs; ApJL accepted