Effect of Inner Crust EoS on Neutron star properties

TL;DR

This study examines how different inner crust equations of state influence neutron star properties, including mass, radius, and deformability, using the relativistic mean-field model, highlighting the crust's role in observable star characteristics.

Contribution

It provides new insights into the impact of inner crust EoS and symmetry energy slope on neutron star radii, deformability, and rotational properties within a relativistic framework.

Findings

Radius at 1.4 solar masses varies by 1-2 km with crust EoS choice.

Low slope parameter crusts produce smaller neutron star radii.

Rotational properties are also affected by crust EoS and slope parameter.

Abstract

The neutron star maximum mass and the radius are investigated within the framework of the relativistic mean-field (RMF) model. The variation in the radius at the canonical mass, $R_{1.4}$, using different inner crust equation of state (EoS) with different symmetry energy slope parameter is studied. It is found that although the NS maximum mass and the corresponding radius do not vary much with different inner crust EoSs, the radius and the tidal deformability at 1.4$M_{\odot}$ vary with the different choice of crust EoS and variation of about 1-2 km is seen in the radius at the canonical mass. For non-unified EoSs, the crust with a low symmetry energy slope parameter produces a low NS radius at the canonical mass. The properties of maximally rotating neutron stars are also studied. The variation in the radius of rotating star at the canonical mass 1.4$M_{\odot}$ is also seen with the slope parameter. Similar to the static neutron star, the radius at 1.4$M_{\odot}$ of rotating neutron star is affected by slope parameter of the inner crust. Other important quantities like moment of inertia, frequency, rotational kinetic energy to gravitational energy ratio are also calculated. The variation in these quantities with the crust slope parameter is found to be more proportional to the mass and the radius of NS.