Two-solar-mass hybrid stars: a two model description with the Nambu-Jona-Lasinio quark model

TL;DR

This paper models hybrid stars with a quark phase using the Nambu-Jona-Lasinio model, demonstrating conditions for 2-solar-mass stars with quark cores and analyzing the impact of vector interactions.

Contribution

It introduces a two-model approach combining hadronic and quark matter descriptions to predict massive hybrid stars with quark cores.

Findings

Vector-isoscalar interactions are essential for 2 solar mass hybrid stars.

Deconfinement and chiral transitions coincide in the model.

Vector-isovector terms lead to larger quark cores and lower deconfinement densities.

Abstract

Hybrid stars with a quark phase described by the Nambu$-$Jona-Lasinio model are studied. The hadron-quark model used to determine the stellar matter equation of state favors the appearance of quark matter: the coincidence of the deconfinement and chiral transitions and a low vacuum constituent quark mass. These two properties are essential to build equations of state that predict pure quark matter in the center of neutron stars. The effect of vector-isoscalar and vector-isovector terms is discussed, and it is shown that the vector-isoscalar terms are necessary to describe 2$M_\odot$ hybrid stars, and the vector-isovector terms result in larger quark cores and a smaller deconfinement density.