On the Deconfinement Phase Transition in Neutron-Star Mergers

TL;DR

This paper investigates the nuclear and quark matter phase transitions during neutron-star mergers using a relativistic model, analyzing the conditions and matter composition in different merger stages.

Contribution

It introduces the use of the Chiral Mean Field model in full general-relativistic simulations to study deconfinement and phase transitions in neutron-star mergers.

Findings

Identification of regions probing different QCD phases during mergers

Analysis of strangeness and entropy generation in phase transitions

Comparison of merger matter with supernova and heavy-ion collision matter

Abstract

We study in detail the nuclear aspects of a neutron-star merger in which deconfinement to quark matter takes place. For this purpose, we make use of the Chiral Mean Field (CMF) model, an effective relativistic model that includes self-consistent chiral symmetry restoration and deconfinement to quark matter and, for this reason, predicts the existence of different degrees of freedom depending on the local density/chemical potential and temperature. We then use the out-of-chemical-equilibrium finite-temperature CMF equation of state in full general-relativistic simulations to analyze which regions of different QCD phase diagrams are probed and which conditions, such as strangeness and entropy, are generated when a strong first-order phase transition appears. We also investigate the amount of electrons present in different stages of the merger and discuss how far from chemical equilibrium they can be and, finally, draw some comparisons with matter created in supernova explosions and heavy-ion collisions.