In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging δ meson to study the influence of δ meson on the cooling properties of neutron star matter. The calculation results show that with the inclusion of δ meson, the neutrino emissivity of the direct Urca processes increases, and thus enhances the cooling of neutron star matter. When strong proton superfluidity is considered, the theoretical cooling curves agree with the observed thermal radiation for isolated neutron stars.
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 presence of the isovector scalar interaction in neutron star matter is considered by exchangingδmeson;we study the effects ofδmesons on the direct Urca processes involving hyperons.The calculation is based on the framework of the relativistic mean field theory.By our analysis,the hyperon direct Urca processes under beta equilibrium are open at lower densities due toδmesons,which create a larger energy gap between two baryons in the reactions.Theδmeson leads to an obvious enhancement of the neutrino emissivity for the hyperon direct Urca processes.In particular,the relativistic neutrino emissivity is found to be substantially larger than predicted in the nonrelativistic approach whetherδmesons appear in an neutron star or not.In our results,δmesons not only change the baryons properties,but also result in more rapid cooling rate of neutron stars by hyperon direct Urca processes.
Yan XuGuang-Zhou LiuCheng-Zhi LiuCun-Bo FanXing-Wei HanXiao-Jun ZhangHong-Yan WangMing-Feng ZhuYu Meng
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
