轴对称黑洞的量子统计熵

避开了求解黑洞背景下波动方程的因难,应用量子统计方法,通过应用在量子引力中、由广义测不准关系得出的新态密度方程,直接求解轴对称Kerr黑洞背景下玻色场和费米场的配分函数.然后,在视界附近计算黑洞背景下玻色场和费米场的熵.得到用收敛级数表达的黑洞熵.在计算中不存在用brick wall模型计算黑洞熵时出现的发散项和小质量近似,使人们对非球对称时空中黑洞的统计熵有更深入的认识. 关键词： 量子统计 非球对称时空 广义测不准关系 黑洞熵     

非奇性Schwarzschild黑洞的零测地线和稳定性

对非奇性Schwarzschild黑洞的零测地线和稳定性进一步进行了研究。结果表明,零测地线和类时测地线一样是完备的,稳定的非奇性黑洞可以存在。 关键词：     

整体正规Schwarzschild黑洞的最大和完备的解析延拓

本文给出了整体正规Schwarzschild黑洞在Kruskal坐标变换中的最大和完备的解析延拓,讨论了零超曲面上的连接条件,比较了奇性和非奇性Schwarzschild黑洞的渐近时空结构。结果表明,可以存在非奇性的稳定的黑洞。 关键词：     

Kerr-Newman-de Sitter黑洞辐射谱和熵修正

本文延拓Damour-Ruffini方法,研究Kerr-Newman-de Sitter黑洞的Hawking辐射.在保持时空中总能量,总角动量和总电荷守恒的条件下,考虑辐射粒子对时空的反作用与黑洞事件视界和宇宙视界的相互关联后,得到了黑洞辐射谱.此辐射不再是严格的纯热谱与黑洞事件视界和宇宙视界对应Bekenstein-Hawking熵变有关.研究发现其结果仍然符合幺正性原理.同时给出了黑洞Bekenstein-Hawking熵的修正项.使人们对黑洞热辐射的研究有了进一步的认识.     

Kerr-Newman-de Sitter黑洞辐射谱和熵修正

本文延拓Damour-Ruffini方法,研究Kerr-Newman-de Sitter黑洞的Hawking辐射.在保持时空中总能量,总角动量和总电荷守恒的条件下,考虑辐射粒子对时空的反作用与黑洞事件视界和宇宙视界的相互关联后,得到了黑洞辐射谱.此辐射不再是严格的纯热谱与黑洞事件视界和宇宙视界对应Bekenstein-Hawking熵变有关.研究发现其结果仍然符合幺正性原理. 同时给出了黑洞Bekenstein-Hawking熵的修正项. 使人们对黑洞热辐射的研究有了进一步的认识.     

静态 dilaton 黑洞中带电磁荷粒子的隧穿效应

利用Parikh 和 Wilczek的隧穿模型,在Gibbons-Maeda dilaton 黑洞时空中,通过计算带有电荷和磁荷的粒子在事件视界上的隧穿概率,研究了该黑洞的Hawking辐射.在粒子的隧穿过程中,强调了时空的能量守恒和电磁荷守恒,考虑了隧穿粒子对背景时空的反作用.计算表明,在Gibbons-Maeda dilaton 黑洞时空中,带电磁荷的粒子通过事件视界的隧穿概率取决于粒子出射前后黑洞熵的变化.这表示,黑洞辐射过程中可以满足信息守恒和量子理论的幺正性. 关键词： 黑洞 霍金辐射 量子理论     

Schwarzschild-de Sitter黑洞的Hawking辐射

利用延拓Damour-Ruffini方法,研究Schwarzschild-de Sitter黑洞的Hawking辐射.在保持时空中总能量守恒的条件下,考虑辐射粒子对时空的反作用和黑洞事件视界与宇宙视界的相互关联后,得到黑洞辐射谱.此辐射不再是严格的纯热谱,与黑洞事件视界和宇宙视界对应Bekenstein-Hawking熵变有关,发现其结果仍然符合幺正性原理. 关键词： Damour-Ruffini方法 Hawking辐射 能量守恒     

非对易时空下Gibbons-Maeda dilaton黑洞和Garfinkle-Horowitz-Strominger dilaton黑洞的热力学性质

以Gibbons-Maeda dilaton黑洞和Garfinkle-Horowitz-Strominger dilaton黑洞为例，研究空间的非对易性对黑洞热力学性质的影响.通过对比对易时空中Gibbons-Maeda dilaton黑洞和非对易时空中Garfinkle-Horowitz-Strominger dilaton黑洞的温度，得出如下结论：从对黑洞热力学性质产生影响这一角度来说，时空的非对易性和黑洞的荷(电荷或磁荷)有相似的作用.     

引力彩虹时空中Kerr黑洞的熵谱和面积谱

利用黑洞的绝热不变性,研究了引力彩虹时空中Kerr黑洞的熵谱和面积谱.首先,在引力彩虹时空背景下,计算了Kerr黑洞的绝热不变作用量,并将其与玻尔-索末菲量子化条件相结合,给出了黑洞的熵谱.得到的熵谱没有引力彩虹时空本身具有的粒子能量依赖性,且是与经典Kerr黑洞中原始贝肯斯坦熵谱相同的等间距熵谱.然后,根据黑洞热力学第一定律和黑洞熵谱,给出了与原始贝肯斯坦谱不同的面积谱.该面积谱是非等间距的,而且有对黑洞面积的依赖性,但不依赖于探测粒子的能量.面积谱表明,随着黑洞面积的减少,面积间隔逐步变小;当黑洞达到普朗克尺度时,面积量子可降为零.这表示黑洞面积不再减少,黑洞出现辐射剩余.而在忽略色散关系的修正效应或在大黑洞极限下,面积谱的修正项可以忽略,引力彩虹Kerr黑洞面积谱可以回归到原始贝肯斯坦谱.此外,对引力彩虹时空Kerr黑洞的熵进行了讨论,得到了带有面积倒数修正项的黑洞熵,分析了黑洞熵的量子修正与面积谱量子修正的一致性.     

类比Ba?ados-Teitelboim-Zanelli黑洞的辐射屏蔽

虽然类比引力理论表明可以使用实验室的物理系统类比黑洞的时空结构,但是旋转黑洞的结构很难在实验室体系中找到较好的对应.本文使用特设的涡旋光,在理论上找到了一种接近Ba?ados-Teitelboim-Zanelli(BTZ)黑洞的类比结构,通过计算无质量粒子和声波在类比BTZ黑洞和引力的BTZ黑洞时空中的运动来比较它们的异同.两种黑洞时空无质量粒子和声波的有效势能给出了相同的能量和角动量的辐射禁区分布,不同的是, BTZ黑洞经典禁区沿径向将趋近固定的能量值,而类比BTZ黑洞的经典禁区沿径向将闭合.幸运的是,在视界和能层附近,无质量粒子和声波的运动行为几乎一致,从这个角度来说,类比实验体系能够很好地模拟BTZ黑洞.特别地,在两种黑洞时空下,低能量高角动量的粒子的经典禁区都更宽.     

Time-like geodesic structure of a spherically symmetric black hole in the brane-world

Recently Malihe Heydari-Fard obtained a spherically symmetric exterior black hole solution in the brane-world scenario, which can be used to explain the galaxy rotation curves without postulating dark matter. By analysing the particle effective potential, we have investigated the time-like geodesic structure of the spherically symmetric black hole in the brane-world. We mainly take account of how the cosmological constant α and the stellar pressure β affect the time-like geodesic structure of the black hole. We find that the radial particle falls to the singularity from a finite distance or plunges into the singularity, depending on its initial conditions. But the non-radial time-like geodesic structure is more complex than the radial case. We find that the particle moves on the bound orbit or stable (unstable) circle orbit or plunges into the singularity, or reflects to infinity, depending on its energy and initial conditions. By comparing the particle effective potential curves for different values of the stellar pressure β and the cosmological constant α, we find that the stellar pressure parameter β does not affect the time-like geodesic structure of the black hole, but the cosmological constant α has an impact on its time-like geodesic structure.     

Connections between abstract quantum theory and space-time structure. III. Vacuum structure and black holes

Quantum-theoretic considerations for the ground state of a black hole result in a change of its interior solution. It is shown that the interior of a Schwarzschild black hole can be modeled by an ur-theoretically described Robertson-Walker space-time. Thereby the Schwarzschild singularity is changed into a Friedman singularity.     

Effective Potential in Noncommutative BTZ Black Hole

In this paper, we investigated the noncommutative rotating BTZ black hole and showed that such a space-time is not maximally symmetric. We calculated effective potential for the massive and the massless test particle by geodesic equations, also we showed effect of non-commutativity on the minimum mass of BTZ black hole.     

Four-Dimensional Dilatonic Black Holes in Gauss-Bonnet Extended String Gravity

An internal singularity of a string four-dimensional black hole with second order curvature corrections is investigated. A restriction to a minimal size of a neutral black hole is obtained in the frame of the model considered. Vacuum polarization of the surrounding space-time caused by this minimal-size black hole is also discussed.     

Investigation the geodesic motion of three dimensional rotating black holes

We study the geodesic equations in the space-time of neutral Brans–Dicke Dilaton black hole in three dimensions and BTZ black hole. We use the process of separation of the Hamilton–Jacobi equation to obtain the constants of motion. The whole analytical solution of the geodesic equations in the space-times of the intended black holes are shown completely. Moreover, the geodesic equations are solved in terms of Weierstrass elliptic functions. Furthermore, with use of the analytical solution and effective potential technique some trajectories around the black holes are classified. Meanwhile, by analytical solution, effective potential and considering the zeroes of underlying polynomials, some possible orbits are plotted. Finally, we compare our results with Cruz et. al. [17] and we indicate the benefits of the analytical method which is applied in this paper.     

What have we learned from two-dimensional models of quantum black holes?

The two-dimensional black hole provides a theoretical laboratory in which the quantum nature of black holes may be probed without the complications of four-dimensional dynamics. It is therefore natural to ask, what have we learned from this model? Much recent work has focused on the semi-classical limit where the black hole is similar to the Schwarzschild solution. However, in this essay, we demonstrate that theexact two-dimensional quantum black hole is non-singular. Instead the singularity is replaced by a surface of time reflection symmetry in an extended space-time. The maximally extended space-time thus consists of an infinite sequence of asymptotically flat regions connected by timelike wormholes, rather analogous to the Reissner-Nordström space-time. The implications of this to the apparent loss of quantum information arising from black hole evaporation are also briefly discussed.     

Black holes in brane worlds

A Kerr metric describing a rotating black hole is obtained on the three brane in a five-dimensional Randall-Sundrum brane world by considering a rotating five-dimensional black string in the bulk. We examine the causal structure of this space-time through the geodesic equations.     

Complex null geodesics in the extended Schwarzschild universe

The generic null geodesic of the Schwarzschild–Kruskal–Szekeres geometry has a natural complexification, an elliptic curve with a cusp at the singularity. To realize that complexification as a Riemann surface without a cusp, and also to ensure conservation of energy at the singularity, requires a branched cover of the space-time over the singularity, with the geodesic being doubled as well to obtain a genus two hyperelliptic curve with an extra involution. Furthermore, the resulting space-time obtained from this branch cover has a Hamiltonian that is null geodesically complete. The full complex null geodesic can be realized in a natural complexification of the Kruskal–Szekeres metric.     

The motion of a gyroscope freely falling into a Schwarzschild black hole

In this note we investigate the motion of the axis of a gyroscope freely falling along the radial geodesic in Schwarzschild space-time. It is shown that the gyroscope's axis rotates to the radial direction in the orthonormal frame as it falls into the black hole.     

Coordinates with Non-Singular Curvature for a Time Dependent Black Hole Horizon

A naive introduction of a dependency of the mass of a black hole on the Schwarzschild time coordinate results in singular behavior of curvature invariants at the horizon, violating expectations from complementarity. If instead a temporal dependence is introduced in terms of a coordinate akin to the river time representation, the Ricci scalar is nowhere singular away from the origin. It is found that for a shrinking mass scale due to evaporation, the null radial geodesics that generate the horizon are slightly displaced from the coordinate singularity. In addition, a changing horizon scale significantly alters the form of the coordinate singularity in diagonal (orthogonal) metric coordinates representing the space-time. A Penrose diagram describing the growth and evaporation of an example black hole is constructed to examine the evolution of the coordinate singularity.