Constraints on color-flavored locked quark matter in view of the HESS J1731-347 event

Abstract

Understanding the processes within compact stars hinges on astrophysical observations. A recent study reported on the central object in the HESS J1731-347 supernova remnant (SNR), estimating a mass of $M=0.77_{-0.17}^{+0.20} \ M_{\odot}$ and a radius of $R=10.40_{-0.78}^{+0.86} \ \rm{km}$, making it the lightest neutron star ever observed. Conventional models suggest that neutron stars form with a minimum gravitational mass of about $1.17M_{\odot}$, raising the question: is this object a typical neutron star, or could it be our first encounter with an "exotic" star? To explore this, we employ the Color-Flavored Locked (CFL) equation of state (EoS), aiming to constrain it by integrating data from the HESS J1731-347 event with pulsar observations and gravitational wave detections. Additionally, we model hybrid EoS by combining the MDI-APR1 (hadronic) and CFL (quark) EoS, incorporating phase transitions via Maxwell construction. Our analysis indicates that CFL quark matter adequately explains all measurements, including the central compact object of HESS J1731-347. In contrast, hybrid models featuring CFL quark phases fail to account for the masses of the most massive observed pulsars.