Disk formation in the collapse of supramassive neutron stars

TL;DR

This paper investigates the formation of accretion disks during the collapse of supramassive neutron stars using equilibrium models and numerical simulations, finding configurations unlikely to produce short gamma-ray bursts.

Contribution

It provides a comprehensive analysis of disk formation in neutron star collapse scenarios across various equations of state, expanding on previous models.

Findings

Broader range of disk forming configurations identified

Most configurations unlikely to produce sGRBs

Supports previous conclusions on the rarity of sGRB-producing collapses

Abstract

Short gamma-ray bursts (sGRBs) show a large diversity in their properties. This suggests that the observed phenomenon can be caused by different "central engines" or that the engine produces a variety of outcomes depending on its parameters, or possibly both. The most popular engine scenario, the merger of two neutron stars, has received support from the recent Fermi and INTEGRAL detection of a burst of gamma rays (GRB170817A) following the neutron star merger GW170817, but at the moment it is not clear how peculiar this event potentially was. Several sGRBs engine models involve the collapse of a supramassive neutron star that produces a black hole plus an accretion disk. We study this scenario for a variety of equations of states both via angular momentum considerations based on equilibrium models and via fully dynamical Numerical Relativity simulations. We obtain a broader range of disk forming configurations than earlier studies but we agree with the latter that none of these configurations is likely to produce a phenomenon that would be classified as an sGRB.