Quark matter nucleation in neutron stars and astrophysical implications

TL;DR

This paper explores the phase transition from hadronic to quark matter in neutron stars, analyzing nucleation mechanisms, energy release, and astrophysical signals like neutrinos and gravitational waves, with implications for star evolution and observable phenomena.

Contribution

It provides a detailed calculation of quark nucleation rates in neutron stars and introduces the concepts of critical mass and limiting temperature for stellar stability.

Findings

Metastability of hadronic stars above a threshold pressure

Energy release of about 10^{53} erg during conversion

Potential signals include neutrino bursts and gravitational waves

Abstract

A phase of strong interacting matter with deconfined quarks is expected in the core of massive neutron stars. We investigate the quark deconfinement phase transition in cold (T = 0) and hot beta-stable hadronic matter. Assuming a first order phase transition, we calculate and compare the nucleation rate and the nucleation time due to quantum and thermal nucleation mechanisms. We show that above a threshold value of the central pressure a pure hadronic star (HS) (i.e. a compact star with no fraction of deconfined quark matter) is metastable to the conversion to a quark star (QS) (i.e. a hybrid star or a strange star). This process liberates an enormous amount of energy, of the order of 10^{53}~erg, which causes a powerful neutrino burst, likely accompanied by intense gravitational waves emission, and possibly by a second delayed (with respect to the supernova explosion forming the HS) explosion which could be the energy source of a powerful gamma-ray burst (GRB). This stellar conversion process populates the QS branch of compact stars, thus one has in the Universe two coexisting families of compact stars: pure hadronic stars and quark stars. We introduce the concept of critical mass M_{cr} for cold HSs and proto-hadronic stars (PHSs), and the concept of limiting conversion temperature for PHSs. We show that PHSs with a mass M < M_{cr} could survive the early stages of their evolution without decaying to QSs. Finally, we discuss the possible evolutionary paths of proto-hadronic stars.