Crustal properties of a neutron star within an effective relativistic mean-field model

TL;DR

This study employs the effective relativistic mean-field model to analyze neutron star crust properties, constructing unified equations of state that align with observational data and highlight the significance of symmetry energy in crustal characteristics.

Contribution

It introduces a unified approach using recent E-RMF parameter sets to accurately model neutron star crusts and their global properties, emphasizing the role of symmetry energy.

Findings

Crustal properties are sensitive to symmetry energy and its slope.

Unified EoSs successfully reproduce observational data from pulsars and NICER.

The models provide consistent estimates for neutron star mass, radius, and crustal features.

Abstract

We use the effective relativistic mean-field (E-RMF) model to study the crustal properties of the neutron star. The unified equations of state (EoS) are constructed using recently developed E-RMF parameter sets, such as FSUGarnet, IOPB-I, and G3. The outer crust composition is determined using the atomic mass evaluation 2020 data [Chinese Physics C {\bf 45}, 030002 (2021)] along with the available Hartree-Fock-Bogoliubov mass models [Phys. Rev. C {\bf 88}, 024308 (2013)] for neutron-rich nuclei. The structure of the inner crust is estimated by performing the compressible liquid drop model calculations using the same E-RMF functional as that for the uniform nuclear matter in the liquid core. Various neutron star properties such as mass-radius ($M-R$) relation, the moment of inertia ($I$), the fractional crustal moment of inertia ($I_{crust}/I$), mass ($M_{crust})$ and thickness ($l_{crust}$) of the crust are calculated with three unified EoSs. The crustal properties are found to be sensitive to the density-dependent symmetry energy and slope parameter advocating the importance of the unified treatment of neutron star EoS. The three unified EoSs, IOPB-I-U, FSUGarnet-U, and G3-U, reproduced the observational data obtained with different pulsars, NICER, and glitch activity and are found suitable for further description of the structure of the neutron star.