Core-crust transition properties of neutron stars within systematically varied extended relativistic mean-field model

TL;DR

This study investigates how the core-crust transition properties of neutron stars depend on nuclear symmetry energy and its slope, using varied extended relativistic mean-field models and a random-phase-approximation method.

Contribution

It systematically analyzes the model and symmetry energy dependence of neutron star transition properties, revealing model-independent correlations with the symmetry energy slope.

Findings

Transition density correlates strongly with the symmetry energy slope at saturation.

Pressure at transition shows weak or model-dependent correlations with symmetry energy parameters.

Correlations with symmetry energy are more significant at sub-saturation densities.

Abstract

The model dependence and the symmetry energy dependence of the core-crust transition properties for the neutron stars are studied using three different families of systematically varied extended relativistic mean field model. Several forces within each of the families are so considered that they yield wide variations in the values of the nuclear symmetry energy $a_{\rm sym}$ and its slope parameter $L$ at the saturation density. The core-crust transition density is calculated using a method based on random-phase-approximation. The core-crust transition density is strongly correlated, in a model independent manner, with the symmetry energy slope parameter evaluated at the saturation density. The pressure at the transition point dose not show any meaningful correlations with the symmetry energy parameters at the saturation density. At best, pressure at the transition point is correlated with the symmetry energy parameters and their linear combination evaluated at the some sub-saturation density. Yet, such correlations might not be model independent. The correlations of core-crust transition properties with the symmetry energy parameter are also studied by varying the symmetry energy within a single model. The pressure at the transition point is correlated once again with the symmetry energy parameter at the sub-saturation density.