Expected neutrino fluence from short Gamma-Ray Burst 170817A and off-axis angle constraints

TL;DR

This paper calculates the expected neutrino emission from GW 170817-associated short gamma-ray burst under different jet models, finding it is generally below detection thresholds and constraining jet parameters based on gamma-ray escape.

Contribution

It provides the first detailed neutrino fluence estimates for GW 170817's gamma-ray burst considering structured and off-axis jet scenarios, and constrains jet parameters using gamma-ray escape limits.

Findings

Neutrino fluence is very low, below current detection sensitivity.

Off-axis angles are constrained by gamma-ray escape and baryonic loading.

Structured jet scenario yields negligible neutrino production.

Abstract

We compute the expected neutrino fluence from SGRB 170817A, associated with the gravitational wave event GW 170817, directly based on Fermi observations in two scenarios: structured jet and off-axis (observed) top-hat jet. While the expected neutrino fluence for the structured jet case is very small, large off-axis angles imply high radiation densities in the jet, which can enhance the neutrino production efficiency. In the most optimistic allowed scenario, the neutrino fluence can reach only $10^{-4}$ of the sensitivity of the neutrino telescopes. We furthermore demonstrate that the fact that gamma-rays can escape limits the baryonic loading (energy in protons versus photons) and the off-axis angle for the internal shock scenario. In particular, for a baryonic loading of ten, the off-axis angle is more strongly constrained by the baryonic loading than by the time delay between the gravitational wave event and the onset of the gamma-ray emission.