Relativistic description of dense matter equation of state and compatibility with neutron star observables: a Bayesian approach

TL;DR

This paper uses a Bayesian approach with relativistic mean field models to analyze the nuclear equation of state and its compatibility with neutron star observations, providing constraints on properties like mass, radius, and tidal deformability.

Contribution

It introduces a Bayesian framework to constrain the dense matter equation of state using minimal nuclear physics constraints and observational data, avoiding exotic degrees of freedom.

Findings

NS mass-radius relationship compatible with GW170817 and NICER data

Maximum neutron star mass estimated at 2.5 solar masses

Speed of sound in dense matter around √(2/3) c

Abstract

The general behavior of the nuclear equation of state (EOS), relevant for the description of neutron stars (NS), is studied within a Bayesian approach applied to a set of models based on a density dependent relativistic mean field description of nuclear matter. The EOS is subjected to a minimal number of constraints based on nuclear saturation properties and the low density pure neutron matter EOS obtained from a precise next-to-next-to-next-to-leading order (N$^{3}$LO) calculation in chiral effective field theory ($\chi$EFT). The posterior distributions of the model parameters obtained under these minimal constraints are employed to construct the distributions of various nuclear matter properties and NS properties such as radii, tidal deformabilites, central energy densities and speeds of sound etc. We found that 90% confidence interval (CI) for allowed NS mass - radius relationship and tidal deformabilites are compatible with GW170817 and recent NICER observations, without invoking the exotic degrees of freedom. A central speed-of-sound of the order of $\sqrt{2/3}$ $c$ is obtained. The maximum neutron star mass allowed by the model is 2.5 $M_\odot$.