Disk mass after a binary neutron star merger as a constraining parameter for short Gamma Ray Bursts

TL;DR

This study uses gamma-ray observations and GW170817 data to estimate disk masses in BNS mergers, revealing many sGRBs likely involve different mechanisms than the one observed in GRB170817A.

Contribution

It introduces a method to constrain disk mass in sGRBs using gamma-ray luminosity and emission times, providing new insights into BNS merger remnants.

Findings

Many sGRBs require unrealistically massive disks based on the model.

The observed BNS merger event suggests alternative mechanisms may be involved in other sGRBs.

Constraints on disk mass challenge the assumption that all sGRBs originate from similar BNS merger remnants.

Abstract

Context. The coincident detection of GW170817 and GRB170817A marked a milestone for the connection between binary neutron star (BNS) mergers and short gamma-ray bursts (sGRBs). These mergers can lead to the formation of a black hole surrounded by a disk and the generation of a powerful jet. It spends energy to break free from the merger ejecta, and then a portion of it, is dissipated to produce observable emissions. Aims. Our primary goal is to enhance our comprehension of BNS mergers by constraining the disk mass for a selection of sGRBs, utilizing isotropic gamma-ray luminosity and corresponding emission times as key indicators. Methods. In this study, we leverage data from GW170817 to estimate the disk mass surrounding the BNS merger remnant and subsequently infer the accretion-to-jet efficiency. Then statistically examine other sGRBs observations to estimate the possibility of being induced by BNS mergers Results. Our findings suggest that, when employing similar physical parameters as in the sole observed BNS-powered GRB event, GRB170817A, a substantial fraction of sGRBs necessitate an unrealistically massive disk remnant. Conclusions. This observation raises the possibility that either a different mechanis