Gamma-ray bursts, cosmic-rays and neutrinos

The γ-ray burst (GRB) model for production of ultra-high-energy, > 1019 eV,cosmic-rays is based on the hypothesis that GRBs arise from the dissipation of the kinetic energy of relativistic fireballs at cosmological distances. Recent observations of delayed low energy emission, ''afterglow,'' from GRB sources strongly support the validity of this hypothesis. Observations also provide quantitative support for the model. The inferred physical fireball parameters imply that protons may be accelerated to > 1020 eV, and the inferred GRB energy generation rate is similar to that required to account for the observed flux of ultra-high-energy cosmic-rays (UHECRs). Strong suppression of cosmic-ray flux is expected in this model above 1019.7 eV, due to proton interaction with microwave background photons. Strong deviations from model flux derived under the assumption of uniform source distribution is expected above 1020 eV, due to source discreteness and due to inhomogeneities in source distribution. In particular, the flux above 1020.5 eV is expected to be dominated by few, narrow spectrum sources. While model predictions can not be tested (with high confidence level) using present data, the predicted signatures should be observed with the planned Auger and Telescope-Array UHECR detectors. A natural consequence of the GRB of the model of UHECR production is the conversion of a large fraction, ∼ 10%, of the fireball energy to accompanying burst of ∼ 1014eV and ∼ 1018eV neutrinos. A km2 neutrino detector would observe several tens of events per year correlated with GRBs, and test for neutrino properties (e.g. flavor oscillations, for which upward moving τ's would be a unique signature, and coupling to gravity) with an accuracy many orders of magnitude better than is currently possible