Constraints on color-flavor locked quark matter in view of the HESS J1731-347 measurement

TL;DR

This study explores whether color-flavor locked quark matter can explain the properties of the lightest observed neutron star, using astrophysical data and theoretical models, and finds that stable CFL quark matter aligns well with observations.

Contribution

It demonstrates that absolutely stable CFL quark matter can account for the observed properties of compact stars, including the lightest neutron star, unlike hybrid models with phase transitions.

Findings

Absolutely stable CFL quark matter explains the HESS J1731-347 measurements.

Hybrid EoS with phase transition cannot reproduce the masses of massive pulsars.

CFL quark matter models are consistent with multiple astrophysical observations.

Abstract

Astrophysical observations play a crucial role in understanding the processes within compact stars. A recent study measured the central object in the HESS J1731-347 supernova remnant (SNR), estimating its mass at $M=0.77^{+0.20}_ {-0.17} \ M_\odot$ and radius at $R = 10.40^{+0.86}_{-0.78} \ \mathrm{km}$, identifying it as the lightest neutron star ever observed. Conventional models suggest neutron stars form with a minimum gravitational mass of approximately $1.17 \ M_\odot$, raising the question of whether this object is a typical neutron star or possibly an "exotic" star. To investigate, we utilize the Color-Flavor Locked (CFL) equation of state (EoS), integrating data from the HESS J1731-347 measurement with pulsar observations and gravitational wave detections. Additionally, we construct hybrid EoS by combining the MDI-APR1 (hadronic) and CFL (quark) EoS, introducing a phase transition through Maxwell construction. Our findings reveal that absolutely stable CFL quark matter effectively explains all observed measurements, including the central object of HESS J1731-347, whereas hybrid models incorporating the CFL MIT Bag model cannot account for the masses of the most massive observed pulsars.