Dependence of the tidal deformability of neutron stars on the nuclear equation of state*

Abstract

Within the Bayesian framework using an explicitly isospin-dependent parametric equation of state (EOS) for the core of neutron stars (NSs), we study how the NS EOS behave when we confront them with the tidal deformabilities $\Lambda_{1.4}$ of canonical NSs with different error and different lower boundaries, and with the tidal deformabilities of the massive NSs. We found that it will not highly improve the constraints on the NS EOS but have a weak effect on narrowing down the slope parameter of the symmetry energy by decreasing the measurement errors of $\Lambda_{1.4}$. Both the isospin-dependent and isospin-independent parts of the NS EOS are significantly constrained and raised as the tidal deformabilities of the massive NSs are adopted in the calculations, especially in high-density regions. It is also found that $\Lambda_{1.4}$ is more competent to limit the curvature parameter than the slope parameter of the symmetry energy, whereas the opposite case happens for the radius of canonical NSs $R_{1.4}$. The tidal deformability of the NS with two times of solar mass $\Lambda_{2.0}$ is more sensitive to the skewness than curvature parameter of the symmetry energy, and $\Lambda_{1.4}$ and $R_{1.4}$ have no correlation with the former.

Systematic analysis of the impacts of symmetry energy parameters on neutron star properties

“…The value of tidal deformability Λ 1.4 is highlighted [7]. Further, we depict the constraints on Λ for NS of mass 1.8M , and 2.0M within 90% CI obtained from ten realistic models that can accurately describe the finite nuclei properties and support the 2M neutron star masses [77,80]. The values of tidal deformability obtained with our minimally constrained EoSs have a reasonable overlap with the ones inferred from the GW170817 event.…”

“…The black line correspond to observational bounds on Λ1.4 = 190 +390 −120 [7]. For the comparison, we have shown violet and gold lines corresponding to Λ1.8 = 70 − 270, and Λ2.0 = 30 − 150 obtained from a few well-motivated theoretical models [77,80] .…”