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
Considering the density dependence of quark mass, we investigate the phase transition between the （unpaired） strange quark matter and the color-flavor-locked matter, which are supposed to be two candidates for the g...Considering the density dependence of quark mass, we investigate the phase transition between the （unpaired） strange quark matter and the color-flavor-locked matter, which are supposed to be two candidates for the ground state of strongly interacting matter. We lind that if the current mass of strange quark m, is smmall, the strange quark matter remains stable unless the baryon density is very high. If m, is large, the phase transition from the strange quark matter to the color-flavor-locked matter in particular to its gapless phase is found to be different from the results predicted by previous works. A complicated phase diagram of three-flavor quark matter is presented, in which the color-flavor-locked phase region is suppressed for moderate densities.展开更多
The origin of the shallow decay segment in γ-ray bursts' (GRB) early light curves remains a mystery, especially those cases with a long-lived plateau followed by an abrupt falloff. In this paper, we propose to un...The origin of the shallow decay segment in γ-ray bursts' (GRB) early light curves remains a mystery, especially those cases with a long-lived plateau followed by an abrupt falloff. In this paper, we propose to understand the origins of the long-lived plateau by considering the solidification of newborn quark stars with latent heat released as energy injection to the GRB afterglow, and we suggest that an abrupt falloff would naturally appear after the plateau due to the energy injection cutoff. We estimated the total latent heat released during the phase transition of quark stars from liquid to solid states to be on the order of ～ 1051 ergs, which is comparable to the emission energy in the shallow decay segment. We also estimated the time scale of radiating the latent heat through thermal photon emission, and found that the time scale agrees with the observations. Based on our estimation, we analyzed the process of energy injection to GRB afterglow. We will show that the steady latent heat of quark star phase transition will continuously inject into the GRB afterglow in a form similar to that of a Poynting-flux-dominated outflow and naturally produce the shallow decay phase and the abrupt falloff after the plateau. We conclude that the latent heat of quark star phase transition is an important contribution to the shallow decay radiation in some GRB afterglows, and explains the long-lived plateau followed by an abrupt falloff, if pulsar-like stars are really (solid) quark stars.展开更多
Direct extrapolation of the strong interaction between quarks in pure perturbative calculation has a problem of thermodynamic inconsistency. A new term determined by thermodynamic consistency requirement could resolve...Direct extrapolation of the strong interaction between quarks in pure perturbative calculation has a problem of thermodynamic inconsistency. A new term determined by thermodynamic consistency requirement could resolve it. This new term plays an important role at lower density in describing the equation of state of quark matter, while it is negligible at high density. Accordingly, the density behavior of the sotmd velocity becomes more reasonable, and the maximum mass of quark stars can be as large as two times the solar mass.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The project supported by National Natural Science Foundation of China under Grant No. 10405012
文摘Considering the density dependence of quark mass, we investigate the phase transition between the （unpaired） strange quark matter and the color-flavor-locked matter, which are supposed to be two candidates for the ground state of strongly interacting matter. We lind that if the current mass of strange quark m, is smmall, the strange quark matter remains stable unless the baryon density is very high. If m, is large, the phase transition from the strange quark matter to the color-flavor-locked matter in particular to its gapless phase is found to be different from the results predicted by previous works. A complicated phase diagram of three-flavor quark matter is presented, in which the color-flavor-locked phase region is suppressed for moderate densities.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10973002, 10973003 and 10935001)the National Basic Research Program of China (Grant Nos. 2009CB24901, 2009CB824800)the John Templeton Foundation and the National Fund for Fostering Talents of Basic Science (Grant No. J0630311)
文摘The origin of the shallow decay segment in γ-ray bursts' (GRB) early light curves remains a mystery, especially those cases with a long-lived plateau followed by an abrupt falloff. In this paper, we propose to understand the origins of the long-lived plateau by considering the solidification of newborn quark stars with latent heat released as energy injection to the GRB afterglow, and we suggest that an abrupt falloff would naturally appear after the plateau due to the energy injection cutoff. We estimated the total latent heat released during the phase transition of quark stars from liquid to solid states to be on the order of ～ 1051 ergs, which is comparable to the emission energy in the shallow decay segment. We also estimated the time scale of radiating the latent heat through thermal photon emission, and found that the time scale agrees with the observations. Based on our estimation, we analyzed the process of energy injection to GRB afterglow. We will show that the steady latent heat of quark star phase transition will continuously inject into the GRB afterglow in a form similar to that of a Poynting-flux-dominated outflow and naturally produce the shallow decay phase and the abrupt falloff after the plateau. We conclude that the latent heat of quark star phase transition is an important contribution to the shallow decay radiation in some GRB afterglows, and explains the long-lived plateau followed by an abrupt falloff, if pulsar-like stars are really (solid) quark stars.
基金supported by the National Natural Science Foundation of China(Grant Nos.11135011 and 11475110)the Key Project from Chinese Academy of Sciences(Grant No.KJCX3-SYW-N2)
文摘Direct extrapolation of the strong interaction between quarks in pure perturbative calculation has a problem of thermodynamic inconsistency. A new term determined by thermodynamic consistency requirement could resolve it. This new term plays an important role at lower density in describing the equation of state of quark matter, while it is negligible at high density. Accordingly, the density behavior of the sotmd velocity becomes more reasonable, and the maximum mass of quark stars can be as large as two times the solar mass.
