Neutron stars with a crossover equation of state

TL;DR

This paper explores a crossover equation of state for neutron stars, inspired by lattice QCD, suggesting it can support stars up to 2.2 solar masses with a quark matter core, avoiding collapse.

Contribution

It introduces a crossover equation of state for neutron stars, differing from traditional first order transition models, and demonstrates its potential to support massive neutron stars.

Findings

Supports neutron stars up to 2.2 solar masses

Quark matter contributes 1-10% of pressure in cores

Crossover EoS prevents collapse unlike first order transitions

Abstract

The question of whether quark matter exists in neutron stars is a long standing one. Generally one finds that a first order phase transition from baryons to quarks softens the equation of state so much that the star would collapse into a black hole. We consider a crossover equation of state, similar to the crossover that is found in lattice QCD studies at finite temperature and zero or small baryon chemical potentials. We find that with reasonable parameters it may be possible to support neutron stars up to about 2.2 solar masses. In that case 1 to 10% of the pressure would be contributed by quark matter in the central core of the highest mass stars.