Astrophysical Implications of the QCD phase transition

TL;DR

This paper explores how a first order QCD phase transition affects neutron star structure and supernova dynamics, suggesting observable signals in neutrino emissions and the potential for a third family of compact stars.

Contribution

It models the QCD phase transition in neutron stars using the NJL model with color superconductivity, revealing new stable configurations and impacts on supernova explosions.

Findings

Presence of a third family of compact stars due to phase transitions.

A second shock wave can be generated during supernova collapse.

QCD phase transition signatures may be observable in neutrino signals.

Abstract

The possible role of a first order QCD phase transition at nonvanishing quark chemical potential and temperature for cold neutron stars and for supernovae is delineated. For cold neutron stars, we use the NJL model with nonvanishing color superconducting pairing gaps, which describes the phase transition to the 2SC and the CFL quark matter phases at high baryon densities. We demonstrate that these two phase transitions can both be present in the core of neutron stars and that they lead to the appearance of a third family of solution for compact stars. In particular, a core of CFL quark matter can be present in stable compact star configurations when slightly adjusting the vacuum pressure to the onset of the chiral phase transition from the hadronic model to the NJL model. We show that a strong first order phase transition can have strong impact on the dynamics of core collapse supernovae. If the QCD phase transition sets in shortly after the first bounce, a second outgoing shock wave can be generated which leads to an explosion. The presence of the QCD phase transition can be read off from the neutrino and antineutrino signal of the supernova.