Massive hybrid stars with a first order phase transition

TL;DR

This paper models the transition to deconfined quark matter in neutron stars, showing how quark interactions influence the phase diagram and enabling the existence of massive hybrid stars with mixed-phase cores.

Contribution

It introduces a detailed model including quark interactions in the equation of state, expanding the mixed phase range and supporting high-mass hybrid stars.

Findings

Quark interactions extend the mixed phase density range.

The equation of state can become stiffer, allowing massive hybrid stars.

The hadron-quark transition is influenced by interaction parameters.

Abstract

We develop our previous study of the transition to deconfined quark phase in neutron stars, including the interaction in the quark equation of state to the leading order in the perturbative expansion within the confinement density-dependent mass model. Using the Gibbs conditions the hadron-quark mixed phase is constructed matching the latter with the hadron equation of state derived from the microscopic Brueckner-Hartree-Fock approximation. The influence of quark interaction parameters on threshold properties and phase diagram of dense neutron star matter are discussed in detail. We find that the leading-order quark interaction expands the density range of the mixed phase, pushing forward the disappearance of the hadron phase. Moreover, since the equation of state could turn out to be stiffer, a high-mass hybrid star is possible with mixed-phase core with typical parameter sets.