XAO OpenIR  > 研究生学位论文
中子星物态方程及其若干天体物理效应
Alternative TitleThe equation of state of neutron star and someastrophysical effects
朱翠
Subtype博士
Thesis Advisor王娜 ; 周霞
2017
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline天体物理
Keyword中子星 物态方程 死亡线 热演化 磁场 电子费米能
Abstract距离脉冲星发现己有50年,观测范围覆盖了从射电波段、X射线、Y射线、紫外、 光学及红外等多波段,以及中微子和引力波探测,并积累了大量的观测数据,发现了 一系列特殊的观测现象。脉冲星丰富的观测特性,使得其理论对应体——中子星成为物理学及天体物理学的独特的天然实验室。物态方程是联系中子星内部微观状态及其 宏观性质的桥梁。磁场和自转在脉冲星类天体的多种辐射过程中起着及其重要的作用。 结合脉冲星各种观测特性,我们讨论了物态方程及磁场对中子星宏观及微观性质的影响。 脉冲星有两个重要的观测参数周期和周期导数,由周期和周期导数可以构成射电脉冲星的P-P关系图。脉冲星的死亡线由脉冲星磁层的加速机制及物态方程等性质决定。一般来说,有射电辐射的脉冲星都应该位于死亡线的上方。而一些特殊的源是射电宁静的脉冲星类天体,也在死亡线上方。脉冲星死亡线与星体的转动惯量I相关,不同中子星的物态方程可以给出不同的脉冲星死亡线。结合丰富的脉冲星类天体的观测 事实,我们讨论了物态方程对死亡线的影响。结果认为X射线暗弱孤立中子星可能是己死亡的磁星,中心致密天体可能是小质量的自束缚奇异星,旋转射电暂现源可能在 死亡线边缘的年老脉冲星。PSRJ2144-3933可能是大质量的脉冲星,甚至质量可能超 过2M☉。多波段观测有助于我们理解脉冲星的基本性质。 中子星转动及热演化实际是耦合在一起的。我们考虑了一种新的中子星转动能转 换通道,即转动能一部分直接通过中微子辐射出去,另外一部分转化为化学能影响中 子星的热演化过程。考虑这种新的转动能转化通道,我们改进了中子星的化学加热机制,重写了热演化和化学演化方程,且给出了中子星热演化曲线和准平衡态下星体的 表面温度。结果表明改进的化学加热机制会使得中子星表面温度有一定程度的升高。 在中子星内部,偏离化学平衡的各种反应过程应考虑中微子辐射直接带走的能量这种新的能量转化通道。 在磁能主导的磁星环境下,我们讨论了电子朗道能级的稳定性及其对电子费米能的影响。磁星的强磁场环境下,电子朗道能级是高度简并的,相对论电子运动的量子化能级。因此,我们新引入参数gn来描述电子朗道能级的稳定性。朗道能级的稳定性系数gn随磁场的增加而减小,电子费米能EF(e)表达式的磁场指数β必须是正数。通过引入Dirac-δ函数,我们推导了超强磁场下的简并的相对论电子费米能的一般 表达式,并且得到了超强磁场下EF(e)特解。这个解给出磁场指数为β=1/6,适用范围ρ≥107gcm-3, Bcr≤B≤1017G。通过修改相对论电子的相空间,超强磁场通过影响电子的重新分布,使得电子数密度ne增加,并且减少电子朗道能级数的最大值。根据泡利不相容原理,简并电子会填充从最低朗道能级到最高朗道能级的所有量子态。随着磁场增强,越来越多的电子将占据朗道能级的高能级,稳定性系数gn随着朗道能级数n增加减小。在超强磁场中,电子数密度增加意味着电子费米能和电子简并压的增加。研究结果可以用于理解中子星内部弱相互作用过程和磁星的磁热演化过程。
Other AbstractSince the first pulsar was discovered 50 years ago, the observation of pulsars cover¬s all bands: radio, X-ray, γ-ray, ultraviolet, optical and infrared bands, including neutrino and gravitational wave detection. While plenty of observation data have been accumulated, people know the properties of neutron stars. The theoretical counterpart of pulsars are neutron s-tars(NSs). Because of abundant observational properties of pulsars, the NSs are the natural laboratories in physics and astrophysics. The equation of state(EoS) is bound up with the in¬ner microscopic matter and the macroscopic properties. Magnetic fields and rotation are two key factors in studying of varied different radiation mechanism from pulsars. In this work, we discuss the EoSs, magnetic field of NSs, as well as various macroscopic and microscopic prop¬erties. Spin period P and the spin-down rate P is two of the most important parameter of pul¬sars. The pulsar death line is defined in the P – P diagram. Many other factors would af¬fect the position of pulsar death line, such as the configuration of surface magnetic field and EoSs. All radio-loud pulsars should be located above the death line which is the radio loud region. With the development of observational equipment, the observational properties of the NSs are remarkably diverse. Some of the special sources are radio quiet but lie above the death line. From the definition of the pulsar death line, different EoSs of NSs result in different pul¬sar death lines, which influence the estimated strength of the surface magnetic fields through the moment of inertia I and radius R. We discussed the influence of EoSs on the pulsar death line and the possible link of different NS groups. The results show that the X-ray Dim Isolated Neutron Stars (XDINSs) could be dead magnetars, Compact Centrak Objects(CCOs) would be small mass of self-bound strange stars (SSs) and rotating radio transients (RRATs) might old pulsars on the verge of death. PSR J2144-3933 are suggested to be large mass pulsars, which would be larger than 2.0 M☉. Multiple observational facts would help us to know the nature of pulsars. The study of NSs binds the kinetic properties and thermodynamic together. We are con-sidered a new channel through which rotational energy is partly converted into neutrinos. With this new energy conversion channel, we improved the chemical heating mechanism which is induced by the spin down of neutron stars, and renew the thermal and chemical evolution e¬quations. The thermal evolution curves and the surface temperature of quasi-equilibrium state are present. The results show that the new energy conversion channel will raise the surface temperature of a neutron star. Moreover, our results suggest that the energy conversion channel induced by the non-equilibrium reaction processes should be taken into account for the study of thermal evolution. We investigate the electron Landau-level stability and its influence on the electron Fer¬mi energy, EF (e), in the circumstance of magnetars, which are powered by magnetic field energy. In a magnetar, the Landau levels of degenerate and relativistic electrons are strong¬ly quantized. A new quantity gn, the electron Landau-level stability coefficient is intro¬duced. According to the requirement that gn decreases with increasing the magnetic field inten¬sity B, the magnetic-field index βin the expression of EF (e) must be positive. By introducing the Dirac-δ function, we deduce a general formulae for the Fermi energy of degenerate and rel¬ativistic electrons, and obtain a particular solution to EF (e) in a superhigh magnetic field. This solution has a low magnetic-field index of β= 1/6, compared with the previous one, and works when ρ≥107gcm-3 and Bcr≤B≤1017Gauss. By modifying the phasespace of relativistic electrons, a superhigh magnetic field can enhance the electron number density ne, and decrease the maximum of electron Landau level number, which results in a redistribution of electron¬s. According to Pauli exclusion principle, the degenerate electrons will fill quantum states from the lowest Landau level to the highest Landau level. As B increases, more and more electrons will occupy higher Landau levels, though gn decreases with the Landau level number n. The enhanced ne in a superhigh magnetic field means an increase in the electron Fermi energy and an increase in the electron degeneracy pressure. The results are expected to facilitate the s¬tudy of the weak interaction processes inside neutron stars and the magnetic-thermal evolution mechanism for megnetars.
Language中文
Document Type学位论文
Identifierhttp://ir.xao.ac.cn/handle/45760611-7/1704
Collection研究生学位论文
科技计划处
Affiliation中国科学院新疆天文台
Recommended Citation
GB/T 7714
朱翠. 中子星物态方程及其若干天体物理效应[D]. 北京. 中国科学院大学,2017.
Files in This Item:
File Name/Size DocType Version Access License
2017届博士学位论文-朱翠.pdf(13180KB) 暂不开放CC BY-NC-SAApplication Full Text
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[朱翠]'s Articles
Baidu academic
Similar articles in Baidu academic
[朱翠]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[朱翠]'s Articles
Terms of Use
No data!
Social Bookmark/Share
All comments (0)
No comment.
 

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.