Neutron stars: from the inner crust to the core with the (Extended) Nambu-Jona-Lasinio model

TL;DR

This paper develops a comprehensive model for neutron star matter using an extended Nambu-Jona-Lasinio approach, incorporating nuclear pasta phases and quark matter, to predict stellar properties consistent with recent observations.

Contribution

It introduces a unified equation of state for neutron star inner crust and core, including nuclear pasta and quark phases, using extended NJL models with various parametrizations.

Findings

Calculated neutron star mass-radius relations aligning with recent data.

Modeled nuclear pasta phases with two different methods.

Described hybrid star quark phases within the su(3) NJL model.

Abstract

Nucleonic matter is described within a su(2) extended Nambu-Jona-Lasinio model. Several parametrizations with different nuclear matter saturation properties are proposed. At subsaturation, nuclear pasta phases are calculated within two methods: the coexistence-phases approximation and the compressible liquid drop model, with the surface tension coefficient determined using a geometrical approach at zero temperature. An unified equation of state of stellar matter for the inner crust, with the nuclear pasta phases, and the core is calculated. The mass and radius of neutron stars within this framework are obtained for several families of hadronic and hybrid stars. The quark phase of hybrid stars is described within the su(3) NJL model including a vector term. Stellar macroscopic properties are in accordance with some of the recent results in the literature.