Hadron-Quark Phase Transition in Quark-Hybrid Stars

TL;DR

This paper investigates the possibility of deconfined quark matter existing in the cores of massive neutron stars, using advanced models to describe phase transitions and predicting mixed phases in stars up to 2.4 solar masses.

Contribution

It introduces a combined modeling approach for hadron-quark phase transition in neutron stars considering vector interactions, predicting mixed phases in high-mass stars.

Findings

Mixed phase of quarks and hadrons can exist in neutron stars up to 2.4 solar masses.

Neutron star radii are predicted to be between 12 and 13 km.

High-mass neutron stars may contain deconfined quark matter in their cores.

Abstract

The recent discovery of the two-solar mass neutron stars $J1614-2230~(1.97 \pm 0.04 M_{\odot})$ and $J0348+0432~(2.01 \pm 0.04 M_{\odot})$ allows to consider the possible existence of deconfined quarks in the cores of neutron stars. Based on a non-local extension of the $SU(3)$ Nambu Jona-Lasinio model with vector interactions to describe the quark matter phase, and a non-linear Walecka model to represent the hadronic phase, a phase transition between these two phases can be constructed via the Gibbs conditions and imposing global electric charge neutrality condition. Depending on the strength of quark vector repulsion, we find that an extended region made of a mixed phase of quarks and hadrons may exist in high-mass neutron stars with masses up to $2.0-2.4 M_{\odot}$. The radii of these objects are between $12$ and $13$ km, as expected for neutron stars.