中子星中质子比例的密度依赖

利用Hartree-Fock理论,基于扩展的Skyrme有效相互作用,采用抛物线近似下对称能的密度相关形式以及β平衡和电中性条件,给出了中子星中质子比例的密度依赖关系.通过比较不同的势参数SII,SIII,SKM和SKI5下对称能强度系数的密度依赖关系研究了中子星中的质子比例,发现在高密时势参数SII,SIII和SKM能够给出中子星中质子消失的结果,这预示着致密核物质可能存在纯中子物质的基态.同时计算表明,考虑中子星中μ^－子的贡献后使质子比例增加.     

低密度物态方程对中子星性质的影响

利用相对论平均场理论描述中子星的液体区域，Fermi气体模型或者FMT，BPS,和BBP模型描述中子星外壳，分别称为Fermi gas+RMF和RMF*，计算了中子星性质并且和相对论平均场理论给出的结果进行比较. 虽然低密度物态方程对中子星最大质量、中心密度、能量密度和压强的影响很小，但是它对中子星的质量半径关系改变很大. 对应中子星的最大质量，RMF和RMF*之间的半径差别为0.23-0.33km.     

热力学过程及物质结构对熵的影响

将宏观过程分解为多个微观过程，可以从多层面的微观角度理解宏观性质。如一般热力学过程的可逆与不可逆性的分解、导致软物质中分子发生凝聚的平移熵、描述非晶过冷及液体中相变区域分子关联运动的构型熵等。反之，利用热力学过程间的耦合原理，通过对微观过程的分解与综合，引入与分子运动相关的动态熵，可以合理地解释各种材料所表现出的不同特性，为制备新材料提供理论依据。     

超子中子星性质的温度效应

从相对论平均场理论出发,考虑核子、超子和介子的相互作用,研究了温度对中子星组成粒子、状态方程和中子星质量等的影响.发现温度越高,超子在中子星内部出现时的重子数密度越低.当密度较高时,中子星的核心区主要由超子组成,即中子星转变成以奇异粒子为主要成分的超子星,并且这种转变受到温度的影响,温度越高,转变密度越低.由于超子的出现,中子星核心高密度区域的状态方程,对于不同温度,差别不大,所以有限温度中子星的最大质量都在1.8M_⊙附近.这与观测结果相符.     

中子星内壳层的物态方程和质子丰度

求解了恒定均匀的强磁场中核子的能谱和波函数，在手征表象中给出含核子反常磁矩(AMM)项的Dirac方程的解；并且计算了中子星内壳层物质的物态方程(EOS)和粒子丰度，发现在强磁场中磁能将使中子星内壳层的压强增加但物质仍然是丰中子，AMM项对质子的极化度有明显效应.     

均匀强磁场中中子星物质的物态方程

在Walecka模型的平均场近似下,研究了由质子、中子和电子组成的中子星物质在均匀强磁场中的性质,发现磁场增强,物态方程会在一定程度上变硬,中子所占比例显著增加,质子和电子所占比例会显著减少,磁场对物态方程的影响比它对粒子组分的影响小.本文还分别利用流体力学公式和热力学公式分别计算了中子星物质的压强,发现磁场越强,用这两种方式计算的压强越接近,当磁场为10¹⁴T时,它们完全重合.     

σ和φ介子对有限温度中子星物质的影响

考虑到σ*,φ介子的贡献及重子八重态{n,p,Λ,Σ^－,Σ⁰,Σ⁺,Ξ^－,Ξ⁰}, 采用相对论平均场方法,在5—25MeV的有限温度范围内, 对中子星物质的性质进行了研究. 发现当考虑到σ*,φ介子的贡献后, 超子出现的临界密度降低了(但对Λ超子, 影响并不显著), 超子的粒子数密度增加了, 在能量密度较高时物态方程变软, 中子星的最大质量变小而相应的半径增大, 中子星的中心粒子数密度、中心能量密度和中心压强都降低了. 当温度为较低的T=5MeV, 10MeV时, σ*,φ介子的参与使出现Σ⁰,Ξ⁰,Σ⁺超子的临界密度极大地降低了; 但当温度为较高的T=15MeV, 20MeV, 25MeV时, 影响则较小. 对于Λ,Σ^－,Ξ^－超子来说, 在上述所有温度下, σ*,φ介子对超子出现的临界密度的影响都不明显.     

致密物质性质和适用于超新星及中子星研究的状态方程(英文)

采用相对论平均场方法研究了致密物质的性质, 构造了包括较宽温度、 同位旋不对称度和密度范围的适用于超新星模拟研究的状态方程, 均匀物质由相对论平均场理论描述, 非均匀物质由托马斯 费米近似给出。讨论了包含超子自由度的中子星物质的状态方程。 计算结果表明, 包含超子可以有效地软化高密度区的状态方程, Λ超子的超流态有可能存在于大质量中子星内部。The properties of dense matter are studied within the relativistic mean field theory. The equation of state (EOS) of dense matter are constructed covering a wide range of temperature, proton fraction, and density for the use of supernova simulations. The relativistic mean field theory is employed to describe the uniform matter, while the Thomas Fermi approximation is adopted to describe the non uniform matter. The EOS of neutron star matter is discussed with the inclusion of hyperons. It is found that the EOS at high density can be significantly softened by the inclusion of hyperons. The 1S₀ superfluidity of Λ hyperons may exist in massive neutron stars.     

σ^＊和Ф介子对有限温度中子星物质的影响

考虑到矿，中介子的贡献及重子八重态{n，p，∧，∑^-，∑^0，∑^＋，≡^-，≡^0}，采用相对论平均场方法，在5—25MeV的有限温度范围内，对中子星物质的性质进行了研究．发现当考虑到σ^＊，Ф介子的贡献后，超子出现的临界密度降低了（但对∧超子，影响并不显著），超子的粒子数密度增加了，在能量密度较高时物态方程变软，中子星的最大质量变小而相应的半径增大，中子星的中心粒子数密度、中心能量密度和中心压强都降低了．当温度为较低的T=5MeV，10MeV时，σ^＊，Ф介子的参与使出现∑^0，≡^0，∑^＋超子的临界密度极大地降低了；但当温度为较高的T=15MeV，20MeV，25MeV时，影响则较小．对于∧，∑^-，≡^-超子来说，在上述所有温度下，矿，中介子对超子出现的临界密度的影响都不明显．     

中子星物质中的K介子凝聚

用密度相关的相对论平均场理论计算了中子星物质中的K介子凝聚,结果表明中子星物质发生K介子凝聚的临界密度约为2.75ρ₀.中子星物质URCA过程发生的临界密度在考虑DB核物质中核子自能动量修正时为ρρ0≈3.16,在不考虑DB核物质中核子自能动量修正时为ρρ0≈2.25,并进一步计算了密度相关的相对论平均场理论两种参数形式对中子星物质状态方程的影响.     

Thermal Dynamics Behavior of Protoneutron Star Matter

In the relativistic σ-ω model, including the vacuum fluctuation of nucleons and σ mesons, the effect of the temperature to the composition and equation of state of protoneutron star matter, nucleon effective mass and chemical potential of neutrons and electrons are studied. We find that the influence of the temperature on the equation of state of protoneutron star matter is indeed small, however, its influence on the composition of protoneutron star, which will contribute to the evolution of protoneutron star, cannot be neglected in low density region. The chemical potentials of neutrons and electrons also depend on the temperature in almost the same density region.     

超子耦合参数对热前中子星物质的影响

在相对论平均场理论框架内,利用Λ超子的结合能和中子星质量的观测数据得到超子标量介子耦合参数χσ的范围是0.33—0.77。在这个范围内, 研究了χσ取不同值时, 包含核子, Λ和Ξ超子的热前中子星（固定单个重子熵s=1）的性质。结果表明, 如果超子耦合参数变大, 前中子星核心温度变高, 中微子丰度变低, 前中子星的亚稳态质量范围变小。如果χσ超过了0.75, 前中子星不可能演变成黑洞。联系SN1987A讨论了这一结果的意义。In the framework of the relativistic mean field theory(RMFT), protoneutron stars with hyperons are studied. To be compatible with neutron star masses, the hyperon scalar coupling χσ should lie in the range of 0.33—0.77. As the hyperon scalar coupling increases, in protoneutron star matter, the core temperature increases whereas the abundance of neutrinos decreases. The metastable mass range of protoneutron stars narrows as the temperature increases. It is found that a protoneutron star cannot subside into a low mass black hole when χσ>0.75. Furthermore, the case of SN1987A is discussed.     

Equation of State of Protoneutron Star with Trapped Neutrinos

The influence of trapped neutrinos on the proto-neutron star is studied in the framework of relativistic mean-field theory. The results show that trapped neutrinos increase proton fraction and make the equation of ๏๏ state of neutron star matter softer when neglecting hyperonic freedom, while suppress the appearance of hyperons and make the equation of state stiffer when including hyperons in the protoneutron star. The maximum mass, compared with cold neutron star which is in beta equilibrium, decreases by 0.06_{M_{\odot}} for non-strange protoneutron star while increases by 0.21_{M_{\odot}} for protoneutron star with hyperons when the relative number of trapped neutrino is 0.4.     

前中子星内的K-凝聚和超子的生成

用相对论平均场下的手征强子模型研究了前中子星内K^-凝聚和超子的生成。结果显示，前中子星内的中微子束缚使得出现K^-凝聚的临界密度推迟到更高的重子密度，而K^-0凝聚无法出现。同时中微子束缚使得前中子星的状态方程变硬，从而前中子星的最大质量变大。如果考虑超子，前中子星内无法出现K^-凝聚，同时系统的状态方程变软（与不含超子的情况相比），从而对应前中子星的最大质量变小。A chiral hadronic model is extended to investigate antikaon condensation and hyperons production of protoneutron stars. Our results show that neutrino trapping makes the critical density of K^- condensation delay to higher density and K^-0 condensation not occur. Meanwhile, the equation of state （EOS） of （proto）neutron star matter considering neutrino trapping is stiffer than the case without neutrino trapping. Therefore the maximum masses of rotoneutron stars with neutrino trapping are larger than those without neutrino trapping. If hyperons are considered, antikaon condensation does not appear in （proto） neutron stars. Meanwhile, the corresponding EOS becomes much softer, and the maximum masses of （proto）neutron stars are smaller than those without hyprons.     

Effects of 5 Meson on Thermal Protoneutron Star Matter

In the framework of the relativistic mean field theory, the effects of the 6 meson on protoneutron star matter with hyperons at finite temperature are investigated. In thermal protoneutron star matter, the 6 field potential increases with density first and then decreases. Fixing the density, the increase of the temperature suppresses the 6 field potential. With the inclusion of the 6 meson, the threshold densities for hyperons become lower and the abundance of trapped neutrinos decreases. The most important effect of the 6 meson is to increase the abundance of hyperons in the inner core range of protoneutron stars. With the rise of the temperature, the density range where the 6 meson plays an important role is narrowed and the effects of the 6 meson are suppressed. Moreover, the protoneutron star mass and radius are nearly not affected by the 6 meson.     

Equation of State of Protoneutron Star Matter

We have calculated the equation of state of protoneutron star matter by using the lowest order constrained variational method. In our calculations, the modern Argonne potential (AV₁₈) together with its older model potential (AV₁₄) are used. It is found that the equation of state for high lepton fraction is stiffer than for low lepton fraction. It is seen that the increasing effect of pressure due to high lepton fraction and due to entropy are comparable. It is shown that the temperature and adiabatic index depend on the values of both entropy and lepton fraction.     

温度对有中微子束缚的致密物质性质的影响

把FST模型应用于温度对有中微子束缚的致密物质性质的研究中.结果表明中微子的束缚使得致密物质系统中的质子含量有所增加,温度对npe系统(无中微子束缚)的质子含量的影响比其对npeν_e系统(有中微子束缚)的影响明显.温度的升高使两个系统的能量密度都有所升高,同时,由它们所组成的前中子星的最大质量和Kepler周期都有一定程度的下降.     

中微子束缚效应对致密物质状态的影响

用手征强子模型研究在中微子束缚情况下对致密物质状态及其对前中子星结构的影响.结果表明中微子束缚效应提高了致密物质中质子的含量,使致密物质的状态方程变软,并使前中子星的最大质量与半径减小     

Influence of Entropy on Composition and Structure of Massive Protoneutron Stars

Adjusting the suitable coupling constants in relativistic mean field (RMF) theory and focusing on thermal effect of an entropy per baryon (S) from 0 to 3, we investigate the composition and structure of massive protoneutron stars corresponding PSR J1614-2230 and PSR J0348+0432. It is found that massive protoneutron stars (PNSs) have more hyperons than cold neutron stars. The entropy per baryon will stiffen the equation of state, and the influence on the pressure is more obvious at low density than high density, while the influence on the energy density is more obvious at high density than low density. It is found that higher entropy will give higher maximum mass, higher central temperature and lower central density. The entropy per baryon changes from 0 to 3, the radius of a PNS corresponding PSR J0348+0432 will increase from 12.86 km to 19.31 km and PSR J1612-2230 will increase from 13.03 km to 19.93 km. The entropy per baryon will raise the central temperature of massive PNSs in higher entropy per baryon, but the central temperature of massive PNSs maybe keep unchanged in lower entropy per baryon. The entropy per baryon will increase the moment of inertia of a massive protoneutron star, while decrease gravitational redshift of a massive neutron star.     

Lowest Order Constrained Variational Calculation of Structure Properties of Protoneutron Star

We calculate the structure properties of protoneutron star such as equation of state, maximum mass, radius and temperature profile using the lowest order constrained variational method. We show that the mass and radius of protoneutron star decrease by decreasing both entropy and temperature. For the protoneutron star, it is shown that the temperature is nearly constant in the core and drops rapidly near the crust.