奇异星R模演化的研究

发布时间：2018-06-28 12:52

  本文选题：奇异星 + r-模不稳定性　； 参考：《华中师范大学》2013年硕士论文

【摘要】：如果奇异夸克物质为宇宙中最稳定的基态这一假设成立,那么完全由夸克物质组成的致密天体——奇异夸克星,将成为致密星旗下的另一个有别于中子星的分支。通过对r-模不稳定性的研究,人们可以从中找到区分奇异星与中子星的信号,本文就着重讨论奇异星r-模演化的相关问题。 由于奇异星相对于中子星有着完全不同的物态,而星体的物态对致密天体内部的热力学,动力学性质有着重要影响,如中微子辐射率,热熔,粘滞等。这些都与奇异星r模的演化有着密切的关系。因此首先有必要对奇异星的状态方程及其对应的星体结构进行研究,以此作为讨论的背景。 在任一个旋转的星体中都存在r模不稳定性。采用小角度展开的方法推导出r模满足的一阶以及二阶的扰动方程。实际上,r模不稳定性与引力波辐射是正反馈的关系,同时星体的粘滞会对r模产生阻尼作用。这一过程中星体主要通过引力波和磁偶极辐射损失角动量。由此可以得到r模和转动演化方程。同时,星体的粘滞耗散是温度依赖的,将r模演化方程与热演化方程耦合可以得到奇异星的r模,转动,以及热演化。我们将一阶以及二阶的计算结果进行比较并分析两者之间的差异。 此外,二阶r模必然会引入较差旋转这种非线性机制。较差旋转能使星体内的流体元沿方位角向产生大尺度的漂移。由于等离子体的磁冻结效应,初始的极向磁场随流体元的漂移不断被扭曲在星体内形成环形磁场。从能量角度讲,实则是r模能量转化为环形磁场的磁能。这种转化可以理解为除星体的粘滞外,一种额外对r模的阻尼机制。其阻尼率由环形磁场能量变化及r模能量决定。在给定星体初始磁场构形情况下,利用二阶的拉格朗日位移可推导出环形磁场以及其磁能的变化,进而得到磁阻尼率。在此基础上我们重新考虑奇异星二阶r模的演化。计算结果表明,无论对于正常奇异星或者色味锁定相奇异星,环形磁场的形成都会缩短r模不稳定性的持续时间。特别对色味锁定相奇异星,由于粘滞受到抑制,磁阻尼对r模的抑制作用就尤为显著(r模存在时问由108年降为10-2年)。相比未考虑环形磁场的二阶r模,环形磁场的引入都不会影响两种相奇异星r模的饱和幅度。对正常奇异星,r模饱和幅度需要通过上述方程组解出；色味锁定奇异星,其r模饱和幅度αsat与较差旋转参量K的关系为：αsat∞(K+2)-1/2。环形磁场对r模的阻尼作用直接减弱了r模引力波辐射对星体的制动效果,对色味锁定相奇异星磁阻尼矩甚至可以储存足够的r模角动量,之后转移给星体导致星体自转加速。另外,我们发现r模仅存在于很早期时,而此时中微子辐射很强(NSS)或表面光子辐射很强(CSS),导致r模的加热效果不明显。奇异星r模的这些演化特征为我们证认和区分这类致密星提供可能的途径。
[Abstract]:If the assumption that the singular quark matter is the most stable ground state in the universe is true, then the singularly quark star, a compact celestial body composed entirely of quark matter, will become another branch of the compact star separate from the neutron star. Through the study of the instability of r-mode, we can find the signal to distinguish the strange star from the neutron star. In this paper, we focus on the discussion of the evolution of the r-mode of the singular star. Because singular stars have completely different physical states relative to neutron stars, the physical states of stars have an important influence on the thermodynamic and kinetic properties of dense celestial bodies, such as neutrino emissivity, heat melting, viscosity and so on. These are closely related to the evolution of the r-module of the singular star. Therefore, it is necessary to study the equation of state of the singular star and its corresponding star structure, as the background of the discussion. R mode instability exists in any rotating star. The perturbation equations of first order and second order for r-norm satisfaction are derived by using the method of small angle expansion. In fact, the instability of the r-mode and the radiation of the gravitational wave are positive feedback, and the viscosity of the star will have a damping effect on the r-mode. In this process, the star loses angular momentum mainly through gravitational waves and magnetic dipole radiation. Thus, the r-mode and rotational evolution equations can be obtained. At the same time, the viscous dissipation of stars is temperature-dependent. The r mode, rotation and thermal evolution of singular stars can be obtained by coupling the r mode evolution equation with the thermal evolution equation. We compare the first and second order results and analyze the difference between them. In addition, the second order r-norm is bound to introduce the nonlinear mechanism of differential rotation. Differential rotation can cause large scale drift of fluid elements along azimuth. Due to the magnetic freezing effect of the plasma, the initial polar magnetic field is distorted to form a ring magnetic field in the star with the drift of the fluid element. From the point of view of energy, the r-mode energy is transformed into the magnetic energy of the ring magnetic field. This transformation can be understood as an additional damping mechanism to the r-mode in addition to the astral viscosity. The damping rate is determined by the energy variation of the annular magnetic field and the r mode energy. Under the given configuration of the initial magnetic field of the star, the variation of the annular magnetic field and its magnetic energy can be deduced by using the second order Lagrangian displacement, and the magnetic damping rate can be obtained. On this basis, we reconsider the evolution of the second order r modules of singular stars. The calculation results show that the formation of ring magnetic field can shorten the duration of r mode instability for normal singular stars or color locked phase singular stars. Especially for the color locked phase singularity star, the suppression effect of the magnetic damping on the r mode is especially obvious because of the viscosity suppression (the r mode is reduced from 108 years to 10 -2 years). Compared with the second order r mode without the annular magnetic field, the saturation amplitude of the two phase strange stars is not affected by the introduction of the ring magnetic field. For the normal singularity star, the saturation amplitude of r mode needs to be solved by the above equations, and the relationship between the r mode saturation amplitude 伪 sat and the differential rotation parameter K is: a sat 鈭，

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