Rapid cooling of the compact star in Cassiopea A as a phase transition in dense QCD

TL;DR

This paper models the rapid cooling of the Cassiopea A compact star as a phase transition in dense QCD matter, explaining its behavior through a transition between different color-superconducting phases.

Contribution

It introduces a novel explanation for the star's fast cooling via a phase transition in dense QCD, fitting observational data with a specific transition temperature.

Findings

Cooling behavior explained by phase transition in dense QCD

Requires a massive star of about 2 solar masses

Fits Cassiopea A observational data

Abstract

We present a model of the compact star in Cassiopea A that accounts for its unusually fast cooling behavior. This feature is interpreted as an enhancement in the neutrino emission triggered by a transition from a fully gapped, two-flavor, color-superconducting phase to a crystalline phase or an alternative gapless, color-superconducting phase. By fine-tuning a single parameter -- the temperature of this transition -- a specific cooling scenario can be selected that fits the Cas A data. Such a scenario requires a massive $M\sim 2M_{\odot}$ star and is, therefore, distinctive from models invoking canonical 1.4 $M_{\odot}$ mass star with nucleonic pairing alone.