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

Abstract

We apply a 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 (${\mathrm{N}}^{3}\mathrm{LO}$) calculation in chiral effective field theory. The tidal deformability and radius of a NS with mass $1--2\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ are found to be strongly correlated with the pressure of $\ensuremath{\beta}$-equilibrated matter at densities higher than the saturation density (${\ensuremath{\rho}}_{0}=0.16\text{ }\text{ }{\mathrm{fm}}^{\ensuremath{-}3}$) in a nearly model-independent manner. These correlations are employed to parametrize the pressure for $\ensuremath{\beta}$-equilibrated matter, around $2{\ensuremath{\rho}}_{0}$, as a function of neutron star mass and the corresponding tidal deformability. The maximum mass of the neutron star is also found to be strongly correlated with the pressure of $\ensuremath{\beta}$-equilibrated matter at densities $\ensuremath{\sim}4.5{\ensuremath{\rho}}_{0}$.