Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electron-Positron Pair Loading and the Origin of the Upstream Magnetic
  Field in GRB Shocks   We investigate here the effects of plasma instabilities driven by rapid
electron/positron pair cascades, which arise in the environment of GRB sources
as a result of back-scattering of a seed fraction of the original spectrum. The
injection of electron/positron pairs induces strong streaming motions in the
ambient medium. One therefore expects the pair-enriched medium ahead of the
forward shock to be strongly sheared on length scales comparable to the
radiation front thickness. Using three-dimensional particle-in-cell
simulations, we show that plasma instabilities driven by these streaming
electron/positron pairs are responsible for the excitation of
near-equipartition, turbulent magnetic fields. Our results reveal the
importance of the electromagnetic filamentation instability in ensuring an
effective coupling between electron/positron pairs and ions, and may help
explain the origin of large upstream fields in GRB shocks.

12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat