Can Ultrahigh Energy Cosmic Rays Come from Gamma-Ray Bursts? II: Cosmic Rays Below the Ankle and Galactic GRB

摘要

The maximum cosmic ray energy achievable by acceleration by a relativisticblast wave is derived. It is shown that forward shocks from long GRB in theinterstellar medium are powerful enough to produce the Galactic cosmic-raycomponent up to the ankle at $4\times 10^{18}$eV, as per an earlier suggestion(Levinson and Eichler, 1993). It is further argued that, were extragalacticlong GRB responsible for the component {\it above} the ankle as well, thecontribution from an occasional Galactic GRB within the solar circle wouldyield more than the observational limits on the outward flux from the solarcircle, unless intermittency and/or beaming causes the present-day contributionto be less than $10^{-3}$ times the time average, and difficulties with theseavoidance scenarios are also noted.