Note on the Normalization of Predicted GRB Neutrino Flux

TL;DR

This paper revises the predicted neutrino flux from gamma-ray bursts by accounting for energy transfer and radiative losses, reducing previous overestimations and aligning predictions with current IceCube observations.

Contribution

It introduces a correction to the normalization of GRB neutrino flux calculations, considering energy dependence and radiative losses, which was previously neglected.

Findings

Corrected neutrino flux estimates are about five times lower.

Revised predictions are consistent with IceCube's null detection.

Highlights need for more observations to test GRBs as cosmic ray sources.

Abstract

We note that the theoretical prediction of neutrinos from gamma-ray bursts (GRBs) by IceCube overestimates the GRB neutrino flux, because they ignore both the energy dependence of the fraction of proton energy transferred to charged pions and the radiative energy loss of secondary pions and muons when calculating the normalization of the neutrino flux. After correction for these facts the GRB neutrino flux is reduced, e.g., by a factor ~5 for typical GRB spectral parameter, and may be consistent with the present zero event detected by IceCube. More observations are important to push the sensitivity below the prediction and test whether GRBs are the sources of ultra-high energy cosmic rays.