Bayesian Model Selection of Neutron Star Equations of State Using Multi-messenger Observations

Abstract

The measurement of the macroscopic properties of a neutron star, whether in binary or in an isolated system, provides us with a key opportunity to place a stringent constraint on its equation of state. In this paper, we perform Bayesian model selection on a wide variety of neutron star equations of state using multi-messenger observations. In particular, (i) we use the mass and tidal deformability measurements from two binary neutron star merger events, GW170817 and GW190425; and (ii) we use the simultaneous mass–radius measurements of PSR J0030+0451 and PSR J0740+6620 by the NICER collaboration, while the latter has been analyzed by the joint NICER/radio/XMM-Newton collaboration. Among the 31 equations of state considered in this analysis, we are able to rule out different variants of the MS1 family, SKI5, H4, and WFF1 decisively, which are either extremely stiff or soft equations of state. The most preferred equation of state model turns out to be AP3 (or MPA1), which predicts the radius and dimensionless tidal deformability of a 1.4 M ⊙ neutron star to be 12.10 (12.50) km and 393 (513), respectively.