發(fā)布時(shí)間：2018-06-28 12:52

  本文選題：奇異星 + r-模不穩(wěn)定性�。� 參考：《華中師范大學(xué)》2013年碩士論文

【摘要】：如果奇異夸克物質(zhì)為宇宙中最穩(wěn)定的基態(tài)這一假設(shè)成立,那么完全由夸克物質(zhì)組成的致密天體——奇異夸克星,將成為致密星旗下的另一個(gè)有別于中子星的分支。通過對(duì)r-模不穩(wěn)定性的研究,人們可以從中找到區(qū)分奇異星與中子星的信號(hào),本文就著重討論奇異星r-模演化的相關(guān)問題。 由于奇異星相對(duì)于中子星有著完全不同的物態(tài),而星體的物態(tài)對(duì)致密天體內(nèi)部的熱力學(xué),動(dòng)力學(xué)性質(zhì)有著重要影響,如中微子輻射率,熱熔,粘滯等。這些都與奇異星r模的演化有著密切的關(guān)系。因此首先有必要對(duì)奇異星的狀態(tài)方程及其對(duì)應(yīng)的星體結(jié)構(gòu)進(jìn)行研究,以此作為討論的背景。 在任一個(gè)旋轉(zhuǎn)的星體中都存在r模不穩(wěn)定性。采用小角度展開的方法推導(dǎo)出r模滿足的一階以及二階的擾動(dòng)方程。實(shí)際上,r模不穩(wěn)定性與引力波輻射是正反饋的關(guān)系,同時(shí)星體的粘滯會(huì)對(duì)r模產(chǎn)生阻尼作用。這一過程中星體主要通過引力波和磁偶極輻射損失角動(dòng)量。由此可以得到r模和轉(zhuǎn)動(dòng)演化方程。同時(shí),星體的粘滯耗散是溫度依賴的,將r模演化方程與熱演化方程耦合可以得到奇異星的r模,轉(zhuǎn)動(dòng),以及熱演化。我們將一階以及二階的計(jì)算結(jié)果進(jìn)行比較并分析兩者之間的差異。 此外,二階r模必然會(huì)引入較差旋轉(zhuǎn)這種非線性機(jī)制。較差旋轉(zhuǎn)能使星體內(nèi)的流體元沿方位角向產(chǎn)生大尺度的漂移。由于等離子體的磁凍結(jié)效應(yīng),初始的極向磁場(chǎng)隨流體元的漂移不斷被扭曲在星體內(nèi)形成環(huán)形磁場(chǎng)。從能量角度講,實(shí)則是r模能量轉(zhuǎn)化為環(huán)形磁場(chǎng)的磁能。這種轉(zhuǎn)化可以理解為除星體的粘滯外,一種額外對(duì)r模的阻尼機(jī)制。其阻尼率由環(huán)形磁場(chǎng)能量變化及r模能量決定。在給定星體初始磁場(chǎng)構(gòu)形情況下,利用二階的拉格朗日位移可推導(dǎo)出環(huán)形磁場(chǎng)以及其磁能的變化,進(jìn)而得到磁阻尼率。在此基礎(chǔ)上我們重新考慮奇異星二階r模的演化。計(jì)算結(jié)果表明,無(wú)論對(duì)于正常奇異星或者色味鎖定相奇異星,環(huán)形磁場(chǎng)的形成都會(huì)縮短r模不穩(wěn)定性的持續(xù)時(shí)間。特別對(duì)色味鎖定相奇異星,由于粘滯受到抑制,磁阻尼對(duì)r模的抑制作用就尤為顯著(r模存在時(shí)問由108年降為10-2年)。相比未考慮環(huán)形磁場(chǎng)的二階r模,環(huán)形磁場(chǎng)的引入都不會(huì)影響兩種相奇異星r模的飽和幅度。對(duì)正常奇異星,r模飽和幅度需要通過上述方程組解出；色味鎖定奇異星,其r模飽和幅度αsat與較差旋轉(zhuǎn)參量K的關(guān)系為：αsat∞(K+2)-1/2。環(huán)形磁場(chǎng)對(duì)r模的阻尼作用直接減弱了r模引力波輻射對(duì)星體的制動(dòng)效果,對(duì)色味鎖定相奇異星磁阻尼矩甚至可以儲(chǔ)存足夠的r模角動(dòng)量,之后轉(zhuǎn)移給星體導(dǎo)致星體自轉(zhuǎn)加速。另外,我們發(fā)現(xiàn)r模僅存在于很早期時(shí),而此時(shí)中微子輻射很強(qiáng)(NSS)或表面光子輻射很強(qiáng)(CSS),導(dǎo)致r模的加熱效果不明顯。奇異星r模的這些演化特征為我們證認(rèn)和區(qū)分這類致密星提供可能的途徑。
[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 偽 sat and the differential rotation parameter K is: a sat 鈭，

本文編號(hào)：2078056