The Fate of the Compact Remnant in Neutron Star Mergers

TL;DR

This paper investigates how the fate of neutron star merger remnants influences gamma-ray burst production and gravitational wave signals, linking astrophysical observations to nuclear matter properties.

Contribution

It combines merger simulations and equation of state studies to predict remnant outcomes and their implications for observable phenomena.

Findings

Black hole formation occurs rapidly for equations of state with maximum neutron star masses below 2.3-2.4 solar masses.

The rate of black hole formation can constrain the nuclear equation of state.

Observations of gravitational waves and gamma-ray bursts can inform the physics of dense nuclear matter.

Abstract

Neutron star (binary neutron star and neutron star - black hole) mergers are believed to produce short-duration gamma-ray bursts. They are also believed to be the dominant source of gravitational waves to be detected by the advanced LIGO and the dominant source of the heavy r-process elements in the universe. Whether or not these mergers produce short-duration GRBs depends sensitively on the fate of the core of the remnant (whether, and how quickly, it forms a black hole). In this paper, we combine the results of merger calculations and equation of state studies to determine the fate of the cores of neutron star mergers. Using population studies, we can determine the distribution of these fates to compare to observations. We find that black hole cores form quickly only for equations of state that predict maximum non-rotating neutron star masses below 2.3-2.4 solar masses. If quick black hole formation is essential in producing gamma-ray bursts, LIGO observed rates compared to GRB rates could be used to constrain the equation of state for dense nuclear matter.