Li, Zhuo 2010 用GeV辐射限制外部环境的磁场

主要内容:

10mG的样子。

精彩摘抄:


文章信息:

· Find Similar Abstracts (with default settings below)

· arXiv e-print (arXiv:1004.0791)

· References in the Article

· Citations to the Article (2) (Citation History)

· Refereed Citations to the Article

· Also-Read Articles (Reads History)

·

· Translate This Page

Title:		The upstream magnetic field of collisionless GRB shocks: constraint by Fermi-LAT observations
Authors:		Li, Zhuo
Publication:		eprint arXiv:1004.0791
Publication Date:		04/2010
Origin:		ARXIV
Keywords:		Astrophysics - High Energy Astrophysical Phenomena
Comment:		7 pages, ApJ submitted, major change of the appendix for general discussion of parameter space
Bibliographic Code:		2010arXiv1004.0791L

Abstract

Long-lived >100MeV emission has been a common feature of most Fermi-LAT detected gamma-ray bursts (GRBs), e.g., detected up to ~10^3s in long GRBs 080916C and 090902B and ~10^2s in short GRB 090510. This emission is consistent with being produced by synchrotron emission of electrons accelerated to high energy by the relativistic collisionless shock propagating into the weakly magnetized medium. Here we show that this high-energy afterglow emission constrains the preshock magnetic field to satisfy 10^0.5n^{9/8}mG<10^2n^{3/8}mG, where n is the preshock density in unit of cm^{-3}, much more stringent than the previous constraint by X-ray afterglow observations on day scale. This suggests that the preshock magnetic field is strongly amplified, most likely by the streaming of high energy shock accelerated particles, and that the postshock magnetic field might be produced by shock compression of the amplified preshock field only.

---

Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)