Hybrid stars from a constrained equation of state

TL;DR

This paper investigates the conditions under which hybrid stars with quark cores can exist, analyzing the nuclear matter equation of state and multi-quark interactions, and finds that low-mass neutron stars may already contain quark matter cores.

Contribution

It introduces a meta-model approach to constrain the nuclear EoS for hybrid stars and explores the impact of multi-quark interactions on their properties.

Findings

Low-mass neutron stars (~1.4 M_sun) can contain quark cores.

Phase transition to deconfinement requires larger skewness and kurtosis.

Multi-quark interactions significantly influence quark core properties.

Abstract

We determine, within a meta-model, the properties of the nuclear matter equation of state (EoS) that allow for a phase transition to deconfinement matter. It is shown that the properties that define the isoscalar channel are the ones that are affected, in particular, a phase transition implies much larger values of the skewness and kurtosis. The effect of multi-quark interaction channels in the description of the quark phase in hybrid stars is also studied. NS properties, such as the mass and radius of the quark core, show an interplay dependence between the 8-quark vector and the 4-quark isovector-vector interactions. We show that low mass NS, $M\sim 1.4 M_\odot$, may already contain a quark core, and satisfy all existing NS observational constraints. We discuss the strangeness content of the quark core and its influence on the speed of sound.