High-energy cosmic rays from gamma-ray burst sources: A stronger case

The suggested association between the sources of gamma-ray bursts (GRBs) and the sources of ultrahigh-energy cosmic rays (UHECRs) is based on two arguments: ( 1) the constraints that UHECR sources must satisfy in order to allow proton acceleration to greater than 10(20) eV are similar to those inferred for GRB sources from gamma-ray observations, and ( 2) the average energy generation rate of UHECRs is similar to the gamma-ray generation rate of GRBs. We show that recent GRB and UHECR observations strengthen both arguments and hence strengthen the suggested association.