Inferring Neutron Star Nuclear Properties from Gravitational-Wave and Gamma-Ray Burst Observations

TL;DR

This study links neutron star merger properties to gamma-ray burst durations by comparing gravitational-wave and gamma-ray observations, revealing a characteristic mass threshold that distinguishes burst types and constrains nuclear matter properties.

Contribution

It introduces a novel method to infer neutron star nuclear properties by combining gravitational-wave and gamma-ray burst data, identifying a key mass threshold influencing burst duration.

Findings

Identifies a neutron star mass threshold at approximately 1.36 solar masses separating burst types.

Shows the robustness of results against observational uncertainties.

Establishes correlations among characteristic masses related to dense nuclear matter.

Abstract

Recent discoveries of long gamma-ray bursts accompanied by kilonova emission prompted interest in understanding their progenitors. If these long-duration bursts arise from neutron star mergers, similar to short gamma-ray bursts, it raises the question of which physical properties govern burst duration. The mass of the merger stands out as a key factor, strongly influencing the lifetime of the merger remnant, which in turn determines the burst duration: lighter mergers that form long-lived remnants produce short bursts, whereas more massive mergers result in short-lived remnants that collapse into black holes, powering longer bursts. In this paper, we compare merger rates from gravitational-wave observations of LIGO-Virgo-KAGRA with the rates of kilonova-associated long and short gamma-ray bursts, to identify a characteristic total neutron star mass that separates the two burst classes at $1.36^{+0.08}_{-0.09}$ (median and 68\% confidence interval) times of the neutron star Tolman-Oppenheimer-Volkoff mass. This result suggests that massive neutron stars could survive an extended period after merger. Our findings are robust against substantial observational uncertainties and model assumptions. Moreover, we uncover correlations among various characteristic masses tied to dense nuclear matter, introducing a novel and independent approach to constrain neutron star nuclear properties through separated and combined gravitational-wave and gamma-ray burst observations.