Electron Acceleration in Relativistic Gamma-Ray Burst Shocks
Open Access
- 6 October 2006
- journal article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 651 (1), L9-L11
- https://doi.org/10.1086/509075
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.Comment: 4 pages, 2 figs; ApJL accepteKeywords
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