【作者】 朱明枫；

【导师】 刘广洲；

【作者基本信息】 吉林大学 ， 理论物理， 2009， 博士

【摘要】 如何区分中子星和奇异星是当前核天体物理研究中的热点课题。本文对目前区分中子星和奇异星的三种主要方法进行了一些研究。一,介质效应及相应的热力学自洽项对奇异星体粘滞系数的影响。考虑介质效应后,我们对奇异夸克物质的热力学方程进行了热力学自洽处理,在压强中发现了一项由夸克的密度相关有效质量引入的压强附加项。它使得奇异夸克物质的体粘滞系数是未考虑热力学自洽的情况的33%,与不考虑介质效应的情况相比增加了1个数量级。二,密度依赖口袋模型中的奇异夸克物质的热力学性质。我们主要考察了密度依赖口袋模型中的热力学自洽问题。由于热力学自洽的要求,我们在压强项中给出了一项由密度依赖的口袋常数所引入的压强附加项。该压强附加项使得奇异星的状态方程偏软,相应的奇异星最大质量和半径更接近脉冲星的正则质量。三,密度依赖参数对裸奇异星电子气层的影响。我们比较了密度依赖口袋模型的热力学自洽解和非热力学自洽解对裸奇异星电子气层的影响发现,在裸奇异星的表面处,热力学自洽的状态方程对应的内外电场与非热力学自洽的状态方程对应的内外电场相比增加了12-20%。热力学自洽的状态方程对应的电子数密度比非自洽的状态方程对应的电子数密度增加了17-20%。我们还讨论了密度依赖参数对裸奇异星的电子气层的影响。通过比较各种密度依赖参数对电子气层的影响发现,密度依赖参数的选择以及热力学自洽项对距离表面约200费米之内的电子气层结构有影响且在表面处差异最大。不同模型对应的外电场在表面处的差异约为30-50%。更多还原

【Abstract】 The conjecture that strange quark matter (SQM) may be the true groundstate of the quantum chromodynamics (QCD) vacuum was proposed nearly threedecades ago. The possible existence of strange stars has attracted manyauthors. It was assumed that all pulsars are strange stars which arecomposed of strange quark matter. If this assumption is proven, bulkquarks are found naturely. In this thesis, the following aspects ofstrange stars have been studied.Firstly, we have discussed the bulk viscosity of strange stars. Thebulk viscosity of interacting strange quark matter is calculated in thelight of strange quark mass dependent on the reaction rate of u + s <->d + u. Based on this, we rederive the bulk viscosity of interacting strangequark matter. The extra pressure terms comes from the interaction betweenquarks are included. If the temperature is lower than 0.01MeV, our resultsare 50% smaller than the un-consistent one and one order of magnitude morethan the results which do not consider the medium effects. If thetemperature is higher or equal to 0.01 MeV, our results are 30% smallerthe un-consistent one and twice more than the results which do not considerthe medium effects.Secondly, we have studied the thermodynamics of strange quark matterwith density dependent bag constant self-consistently in the frameworkof the general ensemble theory and the MIT bag model. In our treatment,an extra pressure term is derived in the expression of pressure. With theadditional term, the zero pressure locates exactly at the lowest energystate, indicating that our treatment is a self-consistently thermodynamictreatment. The self-consistently thermodynamic equations of state (EOS)of strange quark matter in both the normal and color-flavor-locked (CFL) phase are derived. They are both softer than the inconsistent ones.Strange stars in both of the normal and CFL phase have smaller masses andradii in our treatment. It is interesting to find that the energy densityat a star surface in our treatment is much higher than that in theinconsistent treatment for both phases. Consequently, the surfaceproperties and the corresponding observational properties of strangestars in our treatment are different from those in the inconsistenttreatment.Finally, we have compared the effects of self-consistent with theunself-consistent results on the electrosphere of a bare strange star indensity denpendent bag model. It is found that the electric field obtainedby the self-consistent EOS is larger than the electric field obtained bythe unself-consistent EOS about 12-20%. The corresponding electron numberdensity increases about 17-20%. Then we discuss the effects of densitydependent parameters on the structure of the electrosphere of a barestrange star. It is found that the main differences in the structures ofthe electroshpere for different parameters lie in 200 fm from the surface.The largest deviations in the electric field between those models areabout 30-50% on the star surface.更多还原