Multi-GeV Neutrinos from Internal Dissipation in GRB Fireballs

Abstract

Sub-photospheric internal shocks and transverse differences of the bulk Lorentz factor in relativistic fireball models of GRB lead to neutron diffusion relative to protons, resulting in inelastic nuclear collisions. This produces significant fluxes of ~3 GeV muon neutrinos (antineutrinos) and ~2 GeV electron neutrinos (antineutrinos), scaling with the Lorentz factor eta < 400. This extends significantly the parameter space for which neutrinos from inelastic collision are expected, which in the absence of the above effects requires eta > 400. A model with sideways diffusion of neutrons from a slower wind into a fast jet can lead to production of muon and electron neutrinos (antineutrinos) in the 2-25 GeV or higher range, depending on the value of eta. The emission from either of these mechanisms at z~1 may be detectable in suitably densely spaced detectors.