Quark matter and quark star in color-flavor-locked phase

Abstract

In this work, we investigate the thermodynamical properties of the strange quark matter (SQM) and color-flavorlocked (CFL) quark matter under strong magnetic fields within quasiparticle model. We calculate the energy density and the corresponding anisotropic pressure of SQM and CFL quark matter. Our results indicate that CFL quark matter is more stable than SQM, and the pressure of CFL quark matter increases with the energy gap constant ∆. We also find that the oscillation effects coming from the Lowest Landau Level can be reduced when considering increasing the energy gap constant ∆, which cannot be found in SQM at the identical strong magnetic field. The equivalent quark mass for u, d, and s quark and the chemical potential for each flavor of quarks decrease with the energy gap constant ∆, which matches the conclusion that CFL quark matter is more stable than SQM. From the calculation of the magnetars with SQM and CFL quark matter, we find the maximum mass of the magnetars increases with the energy gap constant ∆ for both the longitudinal magnetic field orientation distribution and the transverse magnetic field orientation distribution, and the tidal deformability of the magnetars increases with the increment of ∆. On the other side, the central baryon density of the maximum mass of the magnetars decreases with the increment of ∆. The results also indicate that the mass-radius lines of the CFL quark star can also satisfy the new estimates of the mass-radius region from PSR J0740 + 6620, PSR J0030 + 0451, and HESS J1731-347.