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Title: Simulations of relativistic collisionless shocks: shock structure and particle acceleration

Abstract

We discuss 3D simulations of relativistic collisionless shocks in electron-positron pair plasmas using the particle-in-cell (PIC) method. The shock structure is mainly controlled by the shock's magnetization ('sigma' parameter). We demonstrate how the structure of the shock varies as a function of sigma for perpendicular shocks. At low magnetizations the shock is mediated mainly by the Weibel instability which generates transient magnetic fields that can exceed the initial field. At larger magnetizations the shock is dominated by magnetic reflections. We demonstrate where the transition occurs and argue that it is impossible to have very low magnetization collisionless shocks in nature (in more than one spatial dimension). We further discuss the acceleration properties of these shocks, and show that higher magnetization perpendicular shocks do not efficiently accelerate nonthermal particles in 3D. Among other astrophysical applications, this may pose a restriction on the structure and composition of gamma-ray bursts and pulsar wind outflows.

Authors:
 [1]
  1. Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, PO Box 20450, MS 29, Stanford, CA 94309 (United States)
Publication Date:
OSTI Identifier:
20719686
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 801; Journal Issue: 1; Conference: Conference on astrophysical sources of high energy particles and radiation, Torun (Poland), 20-24 Jun 2005; Other Information: DOI: 10.1063/1.2141897; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ACCELERATION; ASTROPHYSICS; COLLISIONLESS PLASMA; COSMIC GAMMA BURSTS; ELECTRONS; INTERSTELLAR MAGNETIC FIELDS; MAGNETIZATION; PLASMA SIMULATION; PLASMA WAVES; POSITRONS; RELATIVISTIC PLASMA; RELATIVISTIC RANGE; SHOCK WAVES

Citation Formats

Spitkovsky, Anatoly. Simulations of relativistic collisionless shocks: shock structure and particle acceleration. United States: N. p., 2005. Web. doi:10.1063/1.2141897.
Spitkovsky, Anatoly. Simulations of relativistic collisionless shocks: shock structure and particle acceleration. United States. doi:10.1063/1.2141897.
Spitkovsky, Anatoly. Tue . "Simulations of relativistic collisionless shocks: shock structure and particle acceleration". United States. doi:10.1063/1.2141897.
@article{osti_20719686,
title = {Simulations of relativistic collisionless shocks: shock structure and particle acceleration},
author = {Spitkovsky, Anatoly},
abstractNote = {We discuss 3D simulations of relativistic collisionless shocks in electron-positron pair plasmas using the particle-in-cell (PIC) method. The shock structure is mainly controlled by the shock's magnetization ('sigma' parameter). We demonstrate how the structure of the shock varies as a function of sigma for perpendicular shocks. At low magnetizations the shock is mediated mainly by the Weibel instability which generates transient magnetic fields that can exceed the initial field. At larger magnetizations the shock is dominated by magnetic reflections. We demonstrate where the transition occurs and argue that it is impossible to have very low magnetization collisionless shocks in nature (in more than one spatial dimension). We further discuss the acceleration properties of these shocks, and show that higher magnetization perpendicular shocks do not efficiently accelerate nonthermal particles in 3D. Among other astrophysical applications, this may pose a restriction on the structure and composition of gamma-ray bursts and pulsar wind outflows.},
doi = {10.1063/1.2141897},
journal = {AIP Conference Proceedings},
number = 1,
volume = 801,
place = {United States},
year = {Tue Nov 22 00:00:00 EST 2005},
month = {Tue Nov 22 00:00:00 EST 2005}
}