Using gravitational-wave observations and quasi-universal relations to constrain the maximum mass of neutron stars

TL;DR

This paper combines gravitational-wave data and quasi-universal relations to constrain the maximum mass of nonrotating neutron stars, providing bounds that inform the neutron star equation of state without complex electromagnetic modeling.

Contribution

It introduces a simple method using GW observations and quasi-universal relations to estimate neutron star maximum mass bounds, independent of detailed electromagnetic modeling.

Findings

Maximum mass of nonrotating neutron stars is constrained to approximately 2.01-2.16 solar masses.

The method does not rely on numerical simulations of electromagnetic signals.

Results can be refined with future gravitational-wave detections.

Abstract

Combining the GW observations of merging systems of binary neutron stars and quasi-universal relations, we set constraints on the maximum mass that can be attained by nonrotating stellar models of neutron stars. More specifically, exploiting the recent observation of the GW event GW 170817 and drawing from basic arguments on kilonova modeling of GRB 170817A, together with the quasi-universal relation between the maximum mass of nonrotating stellar models $M_{\rm TOV}$ and the maximum mass supported through uniform rotation $M_{\rm max}=\left(1.20^{+0.02}_{-0.05}\right) M_{\rm TOV}$ we set limits for the maximum mass to be $ 2.01^{+0.04}_{-0.04}\leq M_{\rm TOV}/M_{\odot}\lesssim 2.16^{+0.17}_{-0.15}$, where the lower limit in this range comes from pulsar observations. Our estimate, which follows a very simple line of arguments and does not rely on the modeling of the electromagnetic signal in terms of numerical simulations, can be further refined as new detections become available. We briefly discuss the impact that our conclusions have on the equation of state of nuclear matter.