Hybrid stars from a constrained equation of state

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 ~ 1.4M⊙, 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.

Hybrid Equations of State for Neutron Stars with Hyperons and Deltas

“…We make use of a chiral model in which the scalar (attractive) terms are fixed in order to reproduce the vacuum masses of hadrons (baryons and mesons), as well as mesonic decay constants. While vector terms are constrained to reproduce isospin-symmetric matter saturation properties measured in the laboratory, there is still room to vary isovector terms and higher-order vector terms, which do not affect significantly saturation properties, but can be important for astrophysics [4][5][6][7][8][9].…”