Properties of neutron star described by a relativistic $ab~ initio$ model

TL;DR

This paper uses a relativistic ab initio RBHF model with high-precision potentials to calculate neutron star properties, finding results consistent with recent astronomical observations and gravitational wave data.

Contribution

It introduces a self-consistent RBHF approach with updated potentials to accurately predict neutron star characteristics, improving upon conventional methods.

Findings

Maximum neutron star mass around 2.21-2.30 solar masses

Neutron star radius for 1.4 solar masses between 12.34-12.91 km

Tidal deformability for 1.4 solar masses between 485-626

Abstract

Properties of neutron star are investigated by an available relativistic $ab~ initio$ method, i.e., the relativistic Brueckner-Hartree-Fock (RBHF) model, with the latest high-precision relativistic charge-dependent potentials, pvCD-Bonn A, B, C. The neutron star matter is solved within the beta equilibrium and charge neutrality conditions in the framework of RBHF model. Comparing to the conventional treatment, where the chemical potential of lepton was approximately represented by the symmetry energy of nuclear matter, the equation of state (EOS) of neutron star matter in the present self-consistent calculation with pvCD-Bonn B has striking difference above the baryon number density $n_b=0.55$ fm$^{-3}$. However, these differences influence the global properties of neutron star only about $1\%\sim2\%$. Then, three two-body potentials pvCD-Bonn A, B, C, with different tensor components, are systematically applied in RBHF model to calculate the properties of neutron star. It is found that the maximum masses of neutron star are around $2.21\sim2.30M_\odot$ and the corresponding radii are $R =11.18\sim11.72$ km. The radii of $1.4M_\odot$ neutron star are predicated as $R_{1.4} = 12.34\sim12.91$ km and their dimensionless tidal deformabilities are $\Lambda_{1.4} = 485\sim 626$. Furthermore, the direct URCA process in neutron star cooling will happen from $n_b=0.414\sim0.530$ fm$^{-3}$ with the proton fractions, $Y_p=0.136\sim0.138$. All of the results obtained from RBHF model only with two-body pvCD-Bonn potentials completely satisfy various constraints from recent astronomical observations of massive neutron stars, gravitational wave detection (GW 170817), and mass-radius simultaneous measurement (NICER).