GW170817, General Relativistic Magnetohydrodynamic Simulations, and the Neutron Star Maximum Mass

TL;DR

This paper uses recent GRMHD simulations and GW170817 data to constrain the maximum mass of cold, spherical neutron stars, suggesting it is likely between 2.16 and 2.28 solar masses, with implications for neutron star physics.

Contribution

It introduces a new bound on the neutron star maximum mass derived from combining GW170817 data with GRMHD simulations, under minimal assumptions.

Findings

Maximum neutron star mass estimated between 2.16 and 2.28 solar masses.

Derived a bound on the TOV limit using GW170817 and simulations.

Discussed caveats and future directions for refining the estimate.

Abstract

Recent numerical simulations in general relativistic magnetohydrodynamics (GRMHD) provide useful constraints for the interpretation of the GW170817 discovery. Combining the observed data with these simulations leads to a bound on the maximum mass of a cold, spherical neutron star (the TOV limit): ${M_{\rm max}^{\rm sph}}\lesssim 2.74/\beta$, where $\beta$ is the ratio of the maximum mass of a uniformly rotating neutron star (the supramassive limit) over the maximum mass of a nonrotating star. Causality arguments allow $\beta$ to be as high as $1.27$, while most realistic candidate equations of state predict $\beta$ to be closer to $1.2$, yielding ${M_{\rm max}^{\rm sph}}$ in the range $2.16-2.28 M_\odot$. A minimal set of assumptions based on these simulations distinguishes this analysis from previous ones, but leads to a similar estimate. There are caveats, however, and they are enumerated and discussed. The caveats can be removed by further simulations and analysis to firm up the basic argument.