Quark deconfinement in high-mass neutron stars

TL;DR

This study investigates the possibility of quark deconfinement in high-mass neutron stars using an advanced non-local NJL model, predicting mixed quark-hadron phases and pure quark cores in stars with masses around 2 solar masses.

Contribution

It introduces a non-local SU(3) NJL model with vector interactions to better understand quark matter in neutron stars, extending beyond local models.

Findings

High-mass neutron stars can contain mixed quark-hadron matter.

Pure quark cores are possible under certain conditions.

Neutron star radii with quark matter are 12-13 km.

Abstract

In this paper, we explore whether or not quark deconfinement may occur in high-mass neutron stars such as J1614-2230 (1.97 \pm 0.04 M_Sun) and J0348+0432 (2.01 \pm 0.04 M_Sun). Our study is based on a non-local extension of the SU(3) Nambu Jona-Lasinio (n3NJL) model with repulsive vector interactions among the quarks. This model goes beyond the frequently used local version of the Nambu Jona-Lasinio (NJL) model by accounting for several key features of QCD which are not part of the local model. Confined hadronic matter is treated in the framework of non-linear relativistic mean field theory. We find that both the local as well as the non-local NJL model predict the existence of extended regions of mixed quark-hadron (quark-hybrid) matter in high-mass neutron stars with masses of 2.1 to 2.4 M_Sun. Pure quark matter in the cores of neutron stars is obtained for certain parametrizations of the hadronic lagrangian and choices of the vector repulsion among quarks. The radii of high-mass neutron stars with quark-hybrid matter and/or pure quark matter cores in their centers are found to lie in the canonical range of 12 to 13 km.