On Energy Distribution of Two Space-times with Planar and Cylindrical Symmetries

环形、圆柱形和平面黑洞的引力坍缩

Gravitational collapse to toroidal, cylindrical and planar black holes

非球对称物质的引力坍缩必然导致非静态的外部时空。结果表明，在反德西特环向背景下，具有环向拓扑结构的物质发生引力坍缩，形成环向黑洞。根据所提出的分析模型，坍缩物质以辐射形式（无论是标量、中微子、电磁或引力）从外部时空吸收能量。在对环面的一个或两个坐标进行解压缩后，我们得到圆柱形或平面形物质分别坍缩到黑弦或黑膜上的解。这些结果对箍猜想有影响。

附录：能量-动量张量的对称性

Addendum: Symmetries of the energy-momentum tensor

在最近的文献[1-3]中，我们讨论了非静态球对称时空、静态平面对称时空和静态柱对称时空的物质对称性。这些已被分类为两种情况下，当能量动量张量是非退化的，也当它是退化的。在这里，我们添加了一些结果和关于里奇张量的缺失参考文献。

圆柱形黑洞弹跳及其场源

Cylindrical black bounces and their field sources

本研究将Simpson-Visser正则化方法应用于圆柱对称倒置黑洞，并证明其可由幻影标量场与非线性磁场作为源导出，同时推广至Lima等人的黑洞弹跳解。

Geodesics dynamics in the Linet-Tian spacetime with Lambda>0

We analyse the geodesics' dynamics in cylindrically symmetric vacuum spacetimes with Lambda>0 and compare it to the Lambda=0 and Lambda<0 cases. When Lambda>0 there are two singularities in the metric which brings new qualitative features to the dynamics. We find that Lambda=0 planar timelike confined geodesics are unstable against the introduction of a sufficiently large Lambda, in the sense that the bounded orbits become unbounded. In turn, any non-planar radially bounded geodesics are stable for any positive Lambda. We construct global non-singular static vacuum spacetimes in cylindrical sy…

柱面引力波的规范不变哈密顿动力学

Gauge-invariant Hamiltonian dynamics of cylindrical gravitational waves

本文利用柱面引力波模型，对文献[11]提出的如何构造一个双态不变的哈密顿动力学模型进行了验证。起点是Ashtekar和Pierri的作用量，因为它包含边界项，使得它在无穷远处的非平凡变化是可微的。借助于无穷远参数化，规范变换的概念与渐近对称的概念被清楚地分开。描述了渐近对称性和渐近时间的辛几何，并解释了渐近结构在定义狄拉克观测量的哈密顿动力学的零运动框架中的作用。完整的狄拉克观测量与渐近场的发现和行动的渐近对称对他们的计算。简述了相应的量子理论的构造：确定了Fock空间、渐近场的算符、哈密顿量和散射矩阵。

Cylindrically and axially symmetric wormholes. Throats in vacuum?

This brief review discusses the existence conditions of wormhole throats and wormholes as global configurations in general relativity under the assumptions of cylindrical and axial symmetries. It is pointed out, in particular, that wormhole throats can exist in static, cylindrically symmetric space-times under slightly different conditions as compared with spherical symmetry. In cylindrical space-time with rotation, throats can exist in the presence of ordinary matter or even in vacuum; however, there are substantial difficulties in obtaining asymptotically flat wormhole configurations without…

Do the Ricci and energy-momentum tensors have "duality'' in the context of their Lie symmetries?

The Ricci and energy-momentum tensors have the same algebraic symmetries. In the Einstein equations they look ``dual'' to each other, in that interchanging them and inverting the gravitational coupling leaves the equations invariant. It may then be expected that their differential symmetry Lie algebras would also be identical. Using cylindrically symmetric static spacetimes it is shown that they are not identical and neither algebra is a subset of the other.

Spherical and cylindrical solutions in f (T) gravity by Noether Symmetry Approach

We find exact solutions for f (T) teleparallel gravity for the cases of spherically and cylindrically symmetric tetrads. The adopted method is based on the search for Noether symmetries of point-like Lagrangians defined in Jordan and Einstein frames. Constants of motion are used to reduce the dynamical system.We first consider the Lagrangian defined in the Jordan frame for a spherically symmetric tetrad and, by the help of two constants of motion, we eliminate a tetrad potential and integrate the other. The more complicated structure in the Einstein frame is also overcome by the same method. A…

Taub-NUT、近视界极端 Kerr 和漩涡时空之间对称性的双 Wicks 旋转

Double Wick rotations between symmetries of Taub-NUT, near-horizon extreme Kerr, and swirling spacetimes

通过复分析延拓坐标，将 Taub-NUT 的对称性映射到 NHEK 或漩涡宇宙的对称性，揭示了不同时空类别的对称性关系。

The Hilbert space of 3d gravity: quantum group symmetries and observables

We relate three-dimensional loop quantum gravity to the combinatorial quantisation formalism based on the Chern-Simons formulation for three-dimensional Lorentzian and Euclidean gravity with vanishing cosmological constant. We compare the construction of the kinematical Hilbert space and the implementation of the constraints. This leads to an explicit and very interesting relation between the associated operators in the two approaches and sheds light on their physical interpretation. We demonstrate that the quantum group symmetries arising in the combinatorial formalism, the quantum double of …

Interpretation of the Weyl tensor

According to folklore in general relativity, the Weyl tensor can be decomposed into parts corresponding to Newton-like, incoming and outgoing wavelike field components. It is shown here that this one-to-one correspondence does not hold for space-time geometries with cylindrical isometries. This is done by investigating some well-known exact solutions of Einstein's field equations with whole-cylindrical symmetry, for which the physical interpretation is very clear, but for which the standard Weyl interpretation would give contradictory results. For planar or spherical geometries, however, the s…

Families of exact solutions to Vasiliev's 4D equations with spherical, cylindrical and biaxial symmetry

We provide Vasiliev's four-dimensional bosonic higher-spin gravities with six families of exact solutions admitting two commuting Killing vectors. Each family contains a subset of generalized Petrov Type-D solutions in which one of the two so(2) symmetries enhances to either so(3) or so(2,1). In particular, the spherically symmetric solutions are static and we expect one of them to be gauge-equivalent to the extremal Didenko-Vasiliev solution given in arXiv:0906.3898. The solutions activate all spins and can be characterized either via generalized electric and magnetic charges defined asymptot…