Astronomy and Astrophysics – Astrophysics
Scientific paper
1998-12-16
MNRAS 305 (1999), L6
Astronomy and Astrophysics
Astrophysics
Accepted for MNRAS (Letters), with minor revisions. LaTeX, 5 pages, uses mn.sty
Scientific paper
10.1046/j.1365-8711.1999.02566.x
We consider the acceleration of charged particles at the ultra-relativistic shocks, with Lorentz factors \Gamma_s >> 1 relative to the upstream medium, arising in relativistic fireball models of gamma-ray bursts (GRBs). We show that for Fermi-type shock acceleration, particles initially isotropic in the upstream medium can gain a factor of order \Gamma_s^2 in energy in the first shock crossing cycle, but that the energy gain factor for subsequent shock crossing cycles is only of order 2, because for realistic deflection processes particles do not have time to re-isotropise upstream before recrossing the shock. We evaluate the maximum energy attainable and the efficiency of this process, and show that for a GRB fireball expanding into a typical interstellar medium, these exclude the production of ultra-high-energy cosmic rays (UHECRs), with energies in the range 10^{18.5} - 10^{20.5} eV, by the blast wave. We propose, however, that in the context of neutron star binaries as the progenitors of GRBs, relativistic ions from the pulsar wind bubbles produced by these systems could be accelerated by the blast wave. We show that if the known binary pulsars are typical, the maximum energy, efficiency, and spectrum in this case can account for the observed population of UHECRs.
Achterberg Abraham
Gallant Yves A.
No associations
LandOfFree
Ultra-high-energy cosmic ray acceleration by relativistic blast waves 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 Ultra-high-energy cosmic ray acceleration by relativistic blast waves, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ultra-high-energy cosmic ray acceleration by relativistic blast waves will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-703484