Proto-neutron stars with quark cores

TL;DR

This paper models the evolution of proto-neutron stars into cold stars, focusing on the core's phase transition from hadronic matter to quark matter, and constructs equations of state consistent with observed stellar masses.

Contribution

It develops a hybrid equation of state for PNSs including hadron-quark phase transition using Maxwell's construction, considering neutrino effects and observational constraints.

Findings

Identified hadron-quark phase transition during star evolution.

Constructed EoS satisfying 2 solar mass constraint.

Analyzed core composition changes from neutrino-rich to neutrino-poor states.

Abstract

This work investigates the evolution of proto-neutron stars (PNSs) from birth as neutrino-rich objects to maturity as cold-catalyzed neutrino-poor objects with nucleonic and non-nucleonic degrees of freedom. The focus is on the star's core where the nucleons, hyperons, and the $\Delta$-isobars are expected to dissolve into a ``soup" of deconfined quarks, at higher baryon densities, to establish a possible hadron-quark phase transition. We separately calculate the nuclear equations of state (EoS) for the hadronic matter (composed of all the baryon octet and $\Delta$-isobars) and the strange quark matter (SQM) under the same thermodynamic conditions characteristic of PNS and proto-strange star (PSS) evolution and construct the hybrid EoS using Maxwell's construction. The study allows us to determine the hadron-quark phase transitions along the evolution lines of the star. We observed a phase transition from hadronic matter to quark matter (QM) phase when the neutrinos have completely escaped from the star's core. The EoSs utilized are constrained to meet the $2\,\rm M_\odot$ threshold in accordance with the observational data.