Generalized description of neutron star matter with a nucleonic relativistic density functional

Abstract

In this work, we propose a metamodeling technique to nuclear matter on the basis of a relativistic density functional with density-dependent couplings. Identical density dependence for the couplings in both the isoscalar and isovector sectors is employed. We vary the coupling parameters of the model to capture the uncertainties of the empirical nuclear matter parameters at saturation. Then, we construct a large ensemble of unified equations of state in a consistent manner for both clusterized and uniform matter in $\ensuremath{\beta}$ equilibrium at zero temperature. Finally, we calculate neutron star properties to check the consistency with astrophysical observations within a Bayesian framework. Out of the different sets of astrophysical data employed, the constraint on tidal deformability from the GW170817 event was found to be the most stringent in the posteriors of different neutron star properties explored in the present study. We demonstrate in detail the impact of the isovector incompressibility (${K}_{\mathrm{sym}}$) on high-density matter that leads to a considerable variation in the composition of neutron star matter. A couple of selected models with extreme values of ${K}_{\mathrm{sym}}$, which satisfy various modern nuclear physics and neutron star astrophysics constraints, are uploaded in the CompOSE database [S. Typel et al., Phys. Part. Nucl. 46, 633 (2015).] for use by the community.