Prompt TeV neutrinos from dissipative photospheres of gamma-ray bursts

Abstract

Recently, it was suggested that a photospheric component that results from the internal dissipation occurring in the optically thick inner parts of relativistic outflows may be present in the prompt $γ$/X-ray emission of gamma-ray bursts or X-ray flashes. We explore high-energy neutrino emission in this dissipative photosphere model, assuming that the composition of the outflow is baryon-dominated. We find that neutrino emission from proton-proton collision process forms an interesting signature in the neutrino spectra. Under favorable conditions for the shock dissipation site, these low-energy neutrinos could be detected by ${\rm km^3}$ detectors, such as Icecube. Higher energies ($\ga10$ TeV) neutrino emission from proton-proton collision and photo-pion production processes could be significantly suppressed for dissipation at relatively small radii, due to efficient Bethe-Heitler cooling of protons and/or radiative cooling of the secondary mesons in the photosphere radiation. As the dissipation shocks continue further out, high energy neutrinos from photo-pion production process becomes dominant.

Accepted by ApJ Letters, some changes made following the referees' comments, conclusions unchanged. The paper was originally submitted to PRL on June 6 (2008); resubmitted to ApJL on Oct.1 (2008); accepted by ApJL on Dec. 9 (2008)