Combining Electromagnetic and Gravitational-Wave Constraints on Neutron-Star Masses and Radii

TL;DR

This paper combines gravitational-wave and electromagnetic data to jointly infer neutron-star masses and radii, finding consistent results across different observational methods and reducing prior influence on the inferred equations of state.

Contribution

It introduces a joint Bayesian framework that integrates multiple observational data sets to constrain neutron-star properties more robustly.

Findings

Electromagnetic and gravitational-wave data are consistent in constraining neutron-star structure.

Including an intrinsic scattering term slightly broadens the posterior distributions.

Prior effects on mass-radius curves are reduced when combining data sets.

Abstract

We perform a joint Bayesian inference of neutron-star mass and radius constraints based on GW170817, observations of quiescent low-mass X-ray binaries (QLMXBs), photospheric radius expansion X-ray bursts (PREs), and X-ray timing observations of J0030+0451. With this data set, the form of the prior distribution still has an impact on the posterior mass-radius (MR) curves and equation of state (EOS), but this impact is smaller than recently obtained when considering QLMXBs alone. We analyze the consistency of the electromagnetic data by including an "intrinsic scattering" contribution to the uncertainties, and find only a slight broadening of the posteriors. This suggests that the gravitational-wave and electromagnetic observations of neutron-star structure are providing a consistent picture of the neutron-star mass-radius curve and the EOS.