Astronomy and Astrophysics – Astrophysics
Scientific paper
2003-04-02
Astrophys.J.589:L73-L76,2003
Astronomy and Astrophysics
Astrophysics
4 pages, 4 figures, v2: minor modifications, version to appear in ApJL
Scientific paper
10.1086/376353
This paper presents a new method of Monte-Carlo simulations of test particle Fermi acceleration at relativistic shocks. The particle trajectories in tangled magnetic fields are integrated out exactly from entry to exit through the shock, and the conditional probability of return as a function of ingress and egress pitch angles is constructed by Monte-Carlo iteration. These upstream and downstream probability laws are then used in conjunction with the energy gain formula at shock crossing to reproduce Fermi acceleration. For pure Kolmogorov magnetic turbulence upstream and downstream, the spectral index is found to evolve smoothly from s=2.09 +/- 0.02 for mildly relativistic shocks with Lorentz factor Gamma=2 to s=2.26 +/- 0.04 in the ultra-relativistic limit Gamma >> 1. The energy gain is ~Gamma^2 at first shock crossing, and ~2 in all subsequent cycles as anticipated by Gallant & Achterberg (1999). The acceleration timescale is found to be as short as a fraction of Larmor time when Gamma >> 1.
Lemoine Martin
Pelletier Guy
No associations
LandOfFree
Particle transport in tangled magnetic fields and Fermi acceleration at relativistic shocks does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Particle transport in tangled magnetic fields and Fermi acceleration at relativistic shocks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Particle transport in tangled magnetic fields and Fermi acceleration at relativistic shocks will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-124886