Prompt Neutrino Emission from Gamma-Ray Bursts

Recent observations show that some or possibly all long-duration gamma-ray bursts (GRBs) arise from the core collapse of massive stars. In this case, the GRB environments are believed to be preburst stellar winds. We here study prompt neutrino emission from reverse shocks as a result of the interaction of relativistic fireballs with their surrounding wind matter. We find that for reasonable parameters the neutrino differential spectrum ∝ ǫ ν below ∼ 3× 10 eV but the neutrino differential spectrum from 3× 10 to 5× 10 eV steepens by one power of the energy. In addition, the expected flux of upward moving muons produced by neutrino interactions below a detector on the surface of the Earth is ∼ 50 events per year per km, which is about twice as large as that of the previously studied neutrino bursts. Thus, the prompt neutrino emission discussed here may dominate over neutrino emission from internal shocks. Furthermore, these properties are independent of whether the fireballs are isotropic or highly collimated. Subject headings: gamma-rays: bursts – elementary particles – shock waves – stars: mass loss