Self-consistent thermodynamical treatment to strange quark matter with density-dependent bag constant and properties of hybrid stars

Abstract

Thermodynamics of strange quark matter with density-dependent bag parameter is given by making use of MIT bag model, and properties of strange and hybrid stars are investicated by using them. Our results indicate that an extra term should be appended to the pressure expression of strange quark matter but not to the energy density when the bag constant is density-dependent, which assures self-consistency of the system. With this extra term, strange quark matter equations of state soften, gravitational mass and corresponding radius of strange star decrease compared with the inconsistent case. The hybrid star equations of state soften and corresponding mass and radius for hybrid star decrease when this model is used to describe quark phase in hybrid star. These indicate that new thermodynamics for strange quark matter with density-dependent bag parameter has an important influence on properties of strnge star and hybrid star.