Nearly model-independent constraints on dense matter equation of state in a Bayesian approach

TL;DR

This paper uses a Bayesian approach to derive nearly model-independent constraints on the dense matter equation of state, linking neutron star properties like radius and tidal deformability to pressure at various densities.

Contribution

It introduces a Bayesian framework to constrain the neutron star equation of state with minimal assumptions, utilizing chiral effective field theory and correlations with observable properties.

Findings

Strong correlation between neutron star radius, tidal deformability, and pressure at densities above saturation.

Parametrization of the pressure at around twice saturation density based on neutron star observations.

Maximum neutron star mass correlates with pressure at approximately 4.5 times saturation density.

Abstract

We apply Bayesian approach to construct a large number of minimally constrained equations of state (EOSs) and study their correlations with a few selected properties of a neutron star (NS). Our set of minimal constraints includes a few basic properties of saturated nuclear matter and low-density pure neutron matter EOS which is obtained from a precise next-to-next-to-next-to-leading-order (N$^{3}$LO) calculation in chiral effective field theory. The tidal deformability and radius of NS with mass $1-2 M_\odot$ are found to be strongly correlated with the pressure of $\beta$-equilibrated matter at densities higher than the saturation density ($\rho_0 = 0.16$ fm$^{-3}$) in a nearly model-independent manner. These correlations are employed to parametrize the pressure for $\beta$-equilibrated matter, around 2$\rho_0$, as a function of neutron star mass and the corresponding tidal deformability. The maximum mass of neutron star is also found to be strongly correlated with the pressure of $\beta$-equilibrated matter at densities $\sim 4.5\rho_0$.