Massive quarks in neutron stars

We study various neutron star properties using the Color-Dielectric model to describe quark matter. For the baryon sector at low densities we employ the Walecka model. Applying Gibbs criteria to this composite system, we find that, for matter at β-equilibrium, the pure hadronic phase ends at 0.11 fm−3 and that the mixed quark and hadronic phase extends to 0.31 fm−3. The resulting equation of state yields a maximum neutron star mass of 1.59M⊙. A neutron star with total mass of 1.4M⊙ will consist of a crust made of hadronic matter only, a ∼ 1 km thick region of mixed phase and a core composed of pure quark matter. Implications for the cooling of neutron stars are discussed.