A new class of hybrid EoS with multiple critical endpoints for simulations of supernovae, neutron stars and their mergers

TL;DR

This paper introduces a new class of hybrid equations of state for neutron star matter with multiple critical endpoints, enabling improved simulations of supernovae, neutron stars, and mergers by modeling phase transitions between hadronic and quark matter.

Contribution

It presents a novel hybrid EoS model with a two-zone interpolation capturing phase transitions, including color superconductivity, applicable to astrophysical and experimental scenarios.

Findings

Color superconducting quark matter influences supernova evolution.

Finite entropy affects neutron star mass-radius relations.

Hybrid EoS allows exploration of QCD phase diagram regions in astrophysics.

Abstract

We introduce a family of equations of state (EoS) for hybrid neutron star (NS) matter that is obtained by a two-zone parabolic interpolation between a soft hadronic EoS at low densities and a stiff quark matter EoS with color superconductivity at high densities within a finite region of baryonic chemical potentials $\mu_B^h < \mu_B < \mu_B^q$. We consider two scenarios corresponding to a cross-over and a strong first-order transition between quark and hadron phases considered at finite and zero temperatures. This allows us to analyze the effects of finite entropy on the EoS and mass-radius relation of NS. We demonstrate that the formation of a color superconducting state of quark matter drives the evolution of matter in supernovae explosions under the condition of entropy conservation to higher temperatures than in the case of deconfinement to normal quark matter. Within the presented hybrid EoS scenario, regions of the QCD phase diagram may be accessible to supernovae and NS mergers that can be reached also in terrestrial experiments with relativistic heavy ion collisions.