Ultrarelativistic Plasma Shell Collisions in γ‐Ray Burst Sources: Dimensional Effects on the Final Steady State Magnetic Field

Authors

C. H. Jaroschek, Max-Planck-Institute for Extra- terrestrial Physic
H. Lesch, Max-Planck-Institute for Extra- terrestrial Physic
R. A. Treumann, Dartmouth College

Document Type

Article

Publication Date

1-10-2005

Publication Title

Letters of the Astrophysical Journal

Department

Department of Physics and Astronomy

Abstract

Ultrarelativistic electron-positron plasma shell collisions as an integral part of generic γ-ray burst (GRB) fireball models are studied in the framework of self-consistent three-dimensional particle-in-cell simulations. We compare scenarios at moderately relativistic (γ₀ 10) and ultrarelativistic (γ₀ 100) energies that directly correspond to the regimes of internal and external shell collisions, respectively, in GRB synchrotron emission models. Simulated systems comprise 5 × 10⁸ particles, applying a relativistic, fully electromagnetic, massively parallelized code. It is found that Weibel-generated, steady state magnetic equipartition ratios in external collisions reach up to _B ~ 12%, exceeding the respective internal ratios by nearly a power of 10. Enhanced _B yields can be explained theoretically by the effective reduction of dimensionality in the ultrarelativistic limit, i.e., the energy-dependent confinement of the three-dimensional Weibel instability within quasi-two-dimensional plasma shell slices.

DOI

10.1086/426066

Original Citation

C. H. Jaroschek et al 2005 ApJ 618 822

Dartmouth Digital Commons Citation

Jaroschek, C. H.; Lesch, H.; and Treumann, R. A., "Ultrarelativistic Plasma Shell Collisions in γ‐Ray Burst Sources: Dimensional Effects on the Final Steady State Magnetic Field" (2005). Dartmouth Scholarship. 1802.
https://digitalcommons.dartmouth.edu/facoa/1802