Model-dependent high-energy neutrino flux from Gamma-Ray Bursts

TL;DR

This paper compares predictions of neutrino flux from various GRB models with recent IceCube limits, constraining internal shock and dissipative photosphere models, and discusses implications for GRB emission mechanisms.

Contribution

It introduces a general scheme for calculating GRB neutrino flux and compares model predictions with observational limits, highlighting constraints on standard internal shock and dissipative photosphere models.

Findings

Current neutrino limits challenge the standard internal shock model.

Dissipative photosphere models are constrained if cosmic ray luminosity exceeds gamma-ray luminosity.

Future limits could imply high photon-to-proton luminosity ratios or larger emission radii in GRBs.

Abstract

The IceCube Collaboration recently reported a stringent upper limit on the high energy neutrino flux from GRBs, which provides a meaningful constraint on the standard internal shock model. Recent broad band electromagnetic observations of GRBs also challenge the internal shock paradigm for GRBs, and some competing models for gamma-ray prompt emission have been proposed. We describe a general scheme for calculating the GRB neutrino flux, and compare the predicted neutrino flux levels for different models. We point out that the current neutrino flux upper limit starts to constrain the standard internal shock model. The dissipative photosphere models are also challenged if the cosmic ray luminosity from GRBs is at least 10 times larger than the gamma-ray luminosity. If the neutrino flux upper limit continues to go down in the next few years, then it would suggest the following possibilities: 1. the photon-to-proton luminosity ratio in GRBs is anomalously high for shocks, which may be achieved in some dissipative photosphere models and magnetic dissipation models; or 2. the GRB emission site is at a larger radius than the internal shock radius, as expected in some magnetic dissipation models such as the ICMART model.