We study the influence of the model parameters on the phase transitions, the equation of state （EOS）, and the corresponding mass-radius relations in the interior of neutron stars. The numerical analysis shows that t...We study the influence of the model parameters on the phase transitions, the equation of state （EOS）, and the corresponding mass-radius relations in the interior of neutron stars. The numerical analysis shows that the coupling constants of hyperons have a slight influence on the phase transitions and EOS, but an obvious influence on the particle fractions, while the bag constant B and coupling constant g have an important influence on the phase transitions, the EOS, and the mass-radius relations. We find that both the bag constant B and coupling constant g play the same role in the description of the interactions between quarks of hybrid stars. The maximum mass calculated by using the bag constant determined with experimental data （ranging from 175 to 200 MeV） falls in the interval of 1.4 ～1.7 solar mass. The corresponding radius is between 9.3 and 12 km. These results are in agreement with observed values of neutron stars. The possibility of the existence of a third family is discussed. The detection of a third family may provide a signature for a phase transition inside neutron stars.展开更多
In the relativistic mean field approximation,the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degre...In the relativistic mean field approximation,the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the isovector scalar interaction which is considered by exchangingδmeson on the nucleon direct Urca processes in neutron star matter.The results indicate that the existence of hyperons decreases the abundance of protons and leptons and can sharply suppress the neutrino emissivity of the nucleon direct Urca processes,while it has only a little influence on the neutrino luminosity for a fixed neutron star whetherδmesons appear in a neutron star or not.However,the presence ofδmesons can result in obvious growth in the neutrino emissivity and luminosity which will speed up the cooling rate for the nonsuperfluid neutron star.展开更多
We investigate the influence of the energy gap(Δ)of the color-flavor locked(CFL)quark phase on the bulk properties of hybrid stars.The relativistic mean field model is used for hadronic matter and the MIT bag model f...We investigate the influence of the energy gap(Δ)of the color-flavor locked(CFL)quark phase on the bulk properties of hybrid stars.The relativistic mean field model is used for hadronic matter and the MIT bag model for CFL quark matter.In our calculation results,we find that with the increase of the CFL energy gap there exists a transition behavior,which goes from the hadron star range through the transition range into the CFL quark star range.The observation data of PRS J1614-2230 are in the hadron star range(withΔ<40MeV).We also find that with hyperons the equation of state(EOS)for the hybrid star matter with the CFL quark matter core has a small change,which can be disregarded.展开更多
In the relativistic mean field approximation,the relativistic energy losses of the direct Urca processes with nucleons(N-DURCA)and hyperons(Y-DURCA)are studied in the degenerate baryon matter of neutron stars.We inves...In the relativistic mean field approximation,the relativistic energy losses of the direct Urca processes with nucleons(N-DURCA)and hyperons(Y-DURCA)are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the Y-DURCA processes on the N-DURCA processes,and the total neutrino emissivity of neutron star matter.The results show that the existence of hyperons decreases the abundance of protons and leptons,and can sharply suppress the neutrino emissivity of the N-DURCA processes.展开更多
We investigate the nucleon superfluidity in the^(1)S_(0)channel in neutron star matter using the relativistic mean field theory and the BCS theory.We discuss particularly the influence of the isovector scalar interact...We investigate the nucleon superfluidity in the^(1)S_(0)channel in neutron star matter using the relativistic mean field theory and the BCS theory.We discuss particularly the influence of the isovector scalar interaction which is considered by exchangingδmeson on the nucleon superfluidity.It is found that theδmeson leads to a growth of the nucleon^(1)S_(0)pairing energy gaps in a middle density range of the existing nucleon superfluidity.In addition,when the densityρB>0.36 fm^(-3),the proton^(1)S_(0)pairing energy gap obviously decreases.The density range of the proton^(1)S_(0)superfluidity is narrowed due to the presence ofδmesons.In our results,theδmeson not only changes the EOS and bulk properties but also changes the cooling properties of neutron stars.展开更多
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10047001 and 10275029, the State Key Basic Reserch Development Program under Grant No, G2000-0774-07, and the CAS Knowledge Innovation Project under Grant No. KJCX2-N11
文摘We study the influence of the model parameters on the phase transitions, the equation of state （EOS）, and the corresponding mass-radius relations in the interior of neutron stars. The numerical analysis shows that the coupling constants of hyperons have a slight influence on the phase transitions and EOS, but an obvious influence on the particle fractions, while the bag constant B and coupling constant g have an important influence on the phase transitions, the EOS, and the mass-radius relations. We find that both the bag constant B and coupling constant g play the same role in the description of the interactions between quarks of hybrid stars. The maximum mass calculated by using the bag constant determined with experimental data （ranging from 175 to 200 MeV） falls in the interval of 1.4 ～1.7 solar mass. The corresponding radius is between 9.3 and 12 km. These results are in agreement with observed values of neutron stars. The possibility of the existence of a third family is discussed. The detection of a third family may provide a signature for a phase transition inside neutron stars.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11075063,11073033,11247312 and 11103047.
文摘In the relativistic mean field approximation,the relativistic energy losses of the nucleon direct Urca processes are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the isovector scalar interaction which is considered by exchangingδmeson on the nucleon direct Urca processes in neutron star matter.The results indicate that the existence of hyperons decreases the abundance of protons and leptons and can sharply suppress the neutrino emissivity of the nucleon direct Urca processes,while it has only a little influence on the neutrino luminosity for a fixed neutron star whetherδmesons appear in a neutron star or not.However,the presence ofδmesons can result in obvious growth in the neutrino emissivity and luminosity which will speed up the cooling rate for the nonsuperfluid neutron star.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10675024,11075063 and 11265009the National Found for Fostering Talents of Basic Science under Grant No J1103202.
文摘We investigate the influence of the energy gap(Δ)of the color-flavor locked(CFL)quark phase on the bulk properties of hybrid stars.The relativistic mean field model is used for hadronic matter and the MIT bag model for CFL quark matter.In our calculation results,we find that with the increase of the CFL energy gap there exists a transition behavior,which goes from the hadron star range through the transition range into the CFL quark star range.The observation data of PRS J1614-2230 are in the hadron star range(withΔ<40MeV).We also find that with hyperons the equation of state(EOS)for the hybrid star matter with the CFL quark matter core has a small change,which can be disregarded.
基金by the National Natural Science Foundation of China under Grant Nos 10675024 and 11075063the National Fundamental Project for Subsidy Funds of Personnel Training J0730311.
文摘In the relativistic mean field approximation,the relativistic energy losses of the direct Urca processes with nucleons(N-DURCA)and hyperons(Y-DURCA)are studied in the degenerate baryon matter of neutron stars.We investigate the effects of hyperon degrees of freedom and the Y-DURCA processes on the N-DURCA processes,and the total neutrino emissivity of neutron star matter.The results show that the existence of hyperons decreases the abundance of protons and leptons,and can sharply suppress the neutrino emissivity of the N-DURCA processes.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11075063,11073033,11247312 and 11103047.
文摘We investigate the nucleon superfluidity in the^(1)S_(0)channel in neutron star matter using the relativistic mean field theory and the BCS theory.We discuss particularly the influence of the isovector scalar interaction which is considered by exchangingδmeson on the nucleon superfluidity.It is found that theδmeson leads to a growth of the nucleon^(1)S_(0)pairing energy gaps in a middle density range of the existing nucleon superfluidity.In addition,when the densityρB>0.36 fm^(-3),the proton^(1)S_(0)pairing energy gap obviously decreases.The density range of the proton^(1)S_(0)superfluidity is narrowed due to the presence ofδmesons.In our results,theδmeson not only changes the EOS and bulk properties but also changes the cooling properties of neutron stars.
