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Collisionless Weibel shocks and electron acceleration in gamma-ray bursts

Journal Article · · Astrophysical Journal
;  [1];  [2];  [3]
  1. CAVE Lab, Department of Computer Science, University of Tsukuba, Ibaraki 305-8573 (Japan)
  2. Department of Physics, University of Alabama in Huntsville, ZP12, Huntsville, AL 35805 (United States)
  3. LATMOS, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), 11 Boulevard D’Alembert, F-78280 Guyancourt (France)
A study of collisionless external shocks in gamma-ray bursts is presented. The shock structure, electromagnetic field, and process of electron acceleration are assessed by performing a self-consistent 3D particle-in-cell simulation. In accordance with hydrodynamic shock systems, the shock consists of a reverse shock (RS) and forward shock separated by a contact discontinuity. The development and structure are controlled by the ion Weibel instability. The ion filaments are sources of strong transverse electromagnetic fields at both sides of the double shock structure over a length of 30–100 ion skin depths. Electrons are heated up to a maximum energy ϵ{sub ele}≈√(ϵ{sub b}), where ϵ is the energy normalized to the total incoming energy. Jet electrons are trapped in the RS transition region due to the presence of an ambipolar electric field and reflection by the strong transverse magnetic fields in the shocked region. In a process similar to shock surfing acceleration for ions, electrons experience drift motion and acceleration by ion filament transverse electric fields in the plane perpendicular to the shock propagation direction. Ultimately, accelerated jet electrons are convected back into the upstream.
OSTI ID:
22882550
Journal Information:
Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 811; ISSN ASJOAB; ISSN 0004-637X
Country of Publication:
United Kingdom
Language:
English