Is there Quark Matter in (Low-Mass) Pulsars?

TL;DR

This paper investigates the possibility of quark matter existing in low-mass pulsars by analyzing phase transitions in dense matter and their effects on star stability and structure.

Contribution

It introduces models of phase transitions to color superconducting quark matter in compact stars and explores their implications for pulsar observations.

Findings

Stable hybrid star configurations with quark cores are possible.

Low critical densities for quark matter transition align with pulsar mass data.

Quark matter could form during supernova explosions due to favorable conditions.

Abstract

The effect of the QCD phase transition is studied for the mass-radius relation of compact stars and for hot and dense matter at a given proton fraction used as input in core-collapse supernova simulations. The phase transitions to the 2SC and CFL color superconducting phases lead to stable hybrid star configurations with a pure quark matter core. In supernova explosions quark matter could be easily produced due to $\beta$-equilibrium, small proton fractions and nonvanishing temperatures. A low critical density for the phase transition to quark matter is compatible with present pulsar mass measurements.