Tidal deformability and compactness of neutron stars and massive pulsars from semi-microscopic equations of state

Abstract

Tidal deformability measures how NS can comfortably deform as a response to an applied tidal field. We use updated constraints on the mass, radius, and tidal deformability of neutron star (NS) objects and pulsars to examine nuclear equations of state (EOS) based on realistic finite-range M3Y nucleon-nucleon interaction, which have been successfully used to describe low- and high-dense nuclear matter (NM). We then employ these EOSs to examine the impact of tidal deformability and compactness of NSs on their structure. We found that the EOSs from CDM3Y-230 to CDM3Y-330 characterized with the saturation incompressibility ${K}_{0}=230-330$ MeV together yield more limited ranges of tidal deformability and radius for NS objects than their experimentally inferred ranges. For light NS ($M<\text{M}_{\odot}$), both ${k}_{2}$ and $\mathcal{C}$ decreases upon decreasing the NS mass, which enhances its tidal deformability. The stiffness of the NS core matter has shown a minor effect on the tidal deformability of such NS ($M<\text{M}_{\odot}$). An opposite behavior is obtained as an increase in the tidal Love number but a decrease in the more effective compactness of NS ($M>\text{M}_{\odot}$), upon increasing (decreasing) the stiffness of the employed EOS (its mass). This appears as enhanced tidal deformability indicated at a larger radius for NS of stiffer NM and for the lighter NS above $\text{M}_{\odot}$. Unified description of some correlations between tidal deformability, tidal Love number, and NS compactness is provided independent of the details of the considered EOS.