Momentum dependent mean-field dynamics of compressed nuclear matter and neutron stars

TL;DR

This paper develops a momentum-dependent mean-field model for nuclear matter and neutron stars, demonstrating thermodynamic consistency and matching observed neutron star masses.

Contribution

It introduces a generalized energy-momentum tensor within the NLD model, accounting for regulator functions and momentum dependence, and applies it to neutron star matter.

Findings

NLD model describes nuclear matter properties well

Maximum neutron star mass around 2 solar masses

Model aligns with observational constraints

Abstract

Nuclear matter and compact neutron stars are studied in the framework of the non-linear derivative (NLD) model which accounts for the momentum dependence of relativistic mean-fields. The generalized form of the energy-momentum tensor is derived which allows to consider different forms of the regulator functions in the NLD Lagrangian. The thermodynamic consistency of the NLD model is demonstrated for arbitrary choice of the regulator functions. The NLD approach describes the bulk properties of the nuclear matter and compares well with microscopic calculations and Dirac phenomenology. We further study the high density domain of the nuclear equation of state (EoS) relevant for the matter in $\beta$-equilibrium inside neutron stars. It is shown that the low density constraints imposed on the nuclear EoS and by the momentum dependence of the Schr\"odinger-equivalent optical potential lead to a maximum mass of the neutron stars around $M \simeq 2 M_{\odot}$ which accommodates the observed mass of the J1614-2230 millisecond radio pulsar.