The thermodynamics of strange quark matter with density dependent bag constant are studied self-consistently in the framework of the general ensemble theory and the MIT bag model.In our treatment,an additional term is found in the expression of pressure.With the additional term,the zero pressure locates exactly at the lowest energy state,indicating that our treatment is a self-consistently thermodynamic treatment.The self-consistent equations of state of strange quark matter in both the normal and color-flavor-locked phase are derived.They are both softer than the inconsistent ones.Strange stars in both the normal and color-flavor locked phase have smaller masses and radii in our treatment.It is also interesting to find that the energy density at a star surface in our treatment is much higher than that in the inconsistent treatment for both phases.Consequently,the surface properties and the corresponding observational properties of strange stars in our treatment are different from those in the inconsistent treatment.
In this paper,we study the third family of compact stars with the color-flavor locked(CFL)quark core.The relativistic mean field model is used for hadronic matter and the MIT bag model for CFL quark matter.The results of the calculation show a transitional behavior that goes from the hadron star range,through the transition range,into the CFL quark star range.In the transition range,the third family of compact stars with the CFL quark matter core is found in the wide range of the CFL energy gap 100MeV≤<150 MeV.By comparing with early investigations,we argue that the greatest possible third family of compact stars may be the hybrid stars with the CFL quark core.
WANG HongYanLIU GuangZhouWU YaoRuiXU YanZHU MingFengBAO Tmurbagan
In the framework of the relativistic mean field theory, the effects of the δ meson on the direct Urca （DURCA） processes are investigated. In a neutron star, the DURCA processes involving nucleons, A and - can take place while the process involving the 0 can not. With the inclusion of the δ meson, the threshold densities for the DURCA processes become lower. With the δ included, the threshold neutron star mass for the DURCA process among nucleons and electrons becomes smaller while the threshold masses for the processes involving hyperons become larger. When the δ meson is included, the total neutrino emissivity remarkably increases in the density range of 0.32-0.41 fm-3. The total neutrino luminosity increases with the neutron star mass first and then decreases. The neutrino luminosity gets larger with the inclusion of the δ meson. The cooling of the EXO0748-676 is sensitive to the isovector scalar interaction.
The properties of thermal protoneutron star matter including hyperons are investigated in the framework of the relativistic mean field theory (RMFT). In protoneuron star matter, with the increase of the temperature, the critical densities of hyperons decrease, the sequence for appearances of hyperons change, the abundances of hyperons as well as neutrinos increase, and the strong interactions between baryons get weaker. Meanwhile, the abundances of isospin multiple states for nucleons, Σ, and ■ become identical, leading to isospin saturated symmetric matter, respectively. Moreover, if a protoneutron star is born with higher temperature, it is less likely to convert to a black hole.
