Ultra high energy neutrinos from gamma ray bursts

Protons accelerated to high energies in the relativistic shocks that generate gamma ray bursts photoproduce pions, and then neutrinos in situ. I show that ultra high energy neutrinos (> 10^19 eV) are produced during the burst and the afterglow. A larger flux, also from bursts, is generated via photoproduction off CMBR photons in flight but is not correlated with currently observable bursts, appearing as a bright background. Adiabatic/synchrotron losses from protons/pions/muons are negligible. Temporal and directional coincidences with bursts detected by satellites can separate correlated neutrinos from the background.Comment: Adiabatic/synchrotron losses from protons/pions/muons shown to be negligible. Accepted for publication in Phys. Rev. Letters. RevTe

Neutrinos From Individual Gamma-Ray Bursts in the BATSE Catalog

We calculate the neutrino emission from individual gamma-ray bursts observed by the BATSE detector on the Compton Gamma-Ray Observatory. Neutrinos are produced by photoproduction of pions when protons interact with photons in the region where the kinetic energy of the relativistic fireball is dissipated allowing the acceleration of electrons and protons. We also consider models where neutrinos are predominantly produced on the radiation surrounding the newly formed black hole. From the observed redshift and photon flux of each individual burst, we compute the neutrino flux in a variety of models based on the assumption that equal kinetic energy is dissipated into electrons and protons. Where not measured, the redshift is estimated by other methods. Unlike previous calculations of the universal diffuse neutrino flux produced by all gamma-ray bursts, the individual fluxes (compiled at http://www.arcetri.astro.it/~dafne/grb/) can be directly compared with coincident observations by the AMANDA telescope at the South Pole. Because of its large statistics, our predictions are likely to be representative for future observations with larger neutrino telescopes.Comment: 49 pages, 7 figures. Accepted for publication in Astroparticle Physic

Neutrinos from Gamma-Ray Bursts in Pulsar Wind Bubbles: \sim 10^{16} eV

The supranova model for Gamma-Ray Bursts (GRBs) is becoming increasingly more popular. In this scenario the GRB occurs weeks to years after a supernova explosion, and is located inside a pulsar wind bubble (PWB). Protons accelerated in the internal shocks that emit the GRB may interact with the external PWB photons producing pions which decay into \sim 10^{16} eV neutrinos. A km^2 neutrino detector would observe several events per year correlated with the GRBs.Comment: Accepted for publication in PRL. 4 pages, 3 figures, minor change

GeV Photons from Ultra High Energy Cosmic Rays accelerated in Gamma Ray Bursts

Gamma-ray bursts are produced by the dissipation of the kinetic energy of a highly relativistic fireball, via the formation of a collisionless shock. When this happens, Ultra High Energy Cosmic Rays up to 10^20 eV are produced. I show in this paper that these particles produce, via synchrotron emission as they cross the acceleration region, photons up to 300 GeV which carry away a small, ~0.01, but non-negligible fraction of the total burst energy. I show that, when the shock occurs with the interstellar medium, the optical depth to photon-photon scattering, which might cause energy degradation of the photons, is small. The burst thusly produced would be detected at Earth simultaneoulsy with the parent gamma-ray burst, although its duration may differ significantly from that of the lower energy photons. The expected fluences, ~10^{-5}-10^{-6} erg/cm^2 are well within the range of planned detectors. A new explanation for the exceptional burst GRB 940217 is discussed.Comment: Accepted for publication in The Physical Review Letters. 4 pages, RevTeX needed, no figure

On particle acceleration around shocks. I

We derive a relativistically covariant (although not manifestly so) equation for the distribution function of particles accelerated at shocks, which applies also to extremely relativistic shocks, and arbitrarily anisotropic particle distributions. The theory is formulated for arbitrary pitch angle scattering, and reduces to the well--known case for small angle scatterings via a Fokker--Planck approximation. The boundary conditions for the problem are completely reformulated introducing a physically motivated Green's function; the new formulation allows derivation of the particle spectrum both close and far away from the injection energy in an exact way, while it can be shown to reduce to a power--law at large particle energies. The particle spectral index is also recovered in a novel way. Contact is made with the Newtonian treatment.Comment: Accepted for publication in ApJ; minor changes onl