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
Influences of the bag constant on the properties of hybrid stars are investigated by using relativistic mean field theory and the MIT bag model to describe the hadron phase and quark phase in the interior of neutron s...Influences of the bag constant on the properties of hybrid stars are investigated by using relativistic mean field theory and the MIT bag model to describe the hadron phase and quark phase in the interior of neutron stars, respectively. Our results indicate that the onset of hadron-quark phase transition is put off and the appearance of hyperon species is increased with the increase in bag constant. As a result, the hybrid star equation of state for a mixed phase range stiffens whereas that of the quark phase range softens, and the gravitational mass as well as the corresponding radius of hybrid stars are increased obviously. The gravitational mass of a hybrid star is increased from 1.42 M （M is solar mass） to 1.63M and the corresponding radius is changed from 9.1 km to 12.2 km when the bag constant （B1/4） is increased from 170 MeV to 200 MeV. It is interesting to find that hybrid star equations of state become non-smooth when the TM2 parameter sets in the framework of relativistic mean field theory used to describe the hadronic matter, and consequently, the third family of compact stars appear in the mass-radius relations of hybrid stars in the narrow scope of the bag constant from 175 MeV to 180 MeV. These show that the choice of the bag constant in the MIT bag model has significant influence on the properties of hybrid stars.展开更多
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...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.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 (10275029, 10675054)Natural Science Foundation of Henan Education Department (2008A140009)+1 种基金Science Foundation of Nanyang Normal University (nytc2006k98)Natural Science Foundation of Henan Province (112300410187)
文摘Influences of the bag constant on the properties of hybrid stars are investigated by using relativistic mean field theory and the MIT bag model to describe the hadron phase and quark phase in the interior of neutron stars, respectively. Our results indicate that the onset of hadron-quark phase transition is put off and the appearance of hyperon species is increased with the increase in bag constant. As a result, the hybrid star equation of state for a mixed phase range stiffens whereas that of the quark phase range softens, and the gravitational mass as well as the corresponding radius of hybrid stars are increased obviously. The gravitational mass of a hybrid star is increased from 1.42 M （M is solar mass） to 1.63M and the corresponding radius is changed from 9.1 km to 12.2 km when the bag constant （B1/4） is increased from 170 MeV to 200 MeV. It is interesting to find that hybrid star equations of state become non-smooth when the TM2 parameter sets in the framework of relativistic mean field theory used to describe the hadronic matter, and consequently, the third family of compact stars appear in the mass-radius relations of hybrid stars in the narrow scope of the bag constant from 175 MeV to 180 MeV. These show that the choice of the bag constant in the MIT bag model has significant influence on the properties of hybrid stars.
文摘利用强子物质的相对论平均场理论和夸克物质的有效质量口袋模型,研究流夸克质量的选取对混合星性质的影响.结果表明,随着流夸克质量的增大,强子-夸克相变使密度变大,超子种类变多,混合相区域的状态方程变硬,中子星的最大质量及半径变大.当奇异流夸克质量由90 MeV增到200 MeV时,混合星最大质量由1.4M⊙增至1.63M⊙(M⊙=1.99×1030kg为太阳质量),半径由10.24 km增至11.64 km.
基金supported by the National Natural Science Foundation of China(10675024,11075063,11265009)National Fund for Fostering Talents of Basic Science (J1103202)
文摘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.
