2005/03/15 by J. G. Kirk, Kirk, J. G.
Physics and Astronomy · #Astrophysics (astro-ph) #Astrophysics and Cosmic Phenomena #FOS: Physical sciences #Gamma-ray bursts and supernovae #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0503316
Invited talk at 22nd Texas Symposium, Stanford 13-17 Dec. 2004
arxiv created 2005/03/15 · openalex publication_date 2005/03/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A property common to several different astrophysical sources of high-energy gamma-rays is the presence of bulk motion at relativistic speed. The intrinsic spectra of the nonthermal radiating particles also show interesting similarities, with a pronounced hardening towards lower energies. This suggests two distinct acceleration mechanisms could be at work in these sources. At high energies, the stochastic first-order Fermi process at shocks seems to provide a reasonable explanation. I will briefly review the status of this mechanism before discussing the possibility that, at lower energies, non-stochastic acceleration in the induced electric field of a relativistic current sheet plays a role.