(2+1)-Dimensional AdS Black Hole in Grand Canonical Ensemble

We investigate thermodynamics of the (2+1)-dimensional AdS black hole in grand canonical ensemble. In the York's formalism, the black hole is enclosed in a "box" with a finite radius and the boundary temperature, radius and potential are fixed in the grand canonical ensemble. We investigate the thermodynamical properties such as action,entropy, temperature, etc. We only find the stable solution for (2+1)-dimensional AdS black hole and do not find the instanton with the negative heat capacity.

Multiverse/Hyperverse Models: (4 + 1)-Dimensional Landscape (Black Saturns, Bousso-Hawking Nucleation, Gogberashvili Multiverses, Schwarzschild-De Sitter Nurseries) and a (3 + 1)-Dimensional Model for Dark Energy

We consider the Hyperverse as a collection of multiverses in a (4 + 1)-dimensional spacetime with gravitational constant G. Multiverses in our model are bouquets of thin shells (with synchronized intrinsic times). If gis the gravitational constant of a shell Sand εits thickness, then G~εg. The physical universe is supposed to be one of those thin shells inside the local bouquet called Local Multiverse. Other remarkable objects of the Hyperverse are supposed to be black holes, black lenses, black rings and (generalized) Black Saturns. In addition, Schwarzschild-de Sitter multiversal nurseries can be hidden inside those Black Saturns, leading to their Bousso-Hawking nucleation. It also suggests that black holes in our physical universe might harbor embedded (2 + 1)-dimensional multiverses. This is compatible with outstanding ideas and results of Bekenstein, Hawking-Vaz and Corda about “black holes as atoms” and the condensation of matter on “apparent horizons”. It allows us to formulate conjecture 12.1 about the origin of the Local Multiverse. As an alternative model, we examine spacetime warping of our universe by external universes. It gives data for the accelerated expansion and the cosmological constant Λ, which are in agreement with observation, thus opening a possibility for verification of the multiverse model.

Gravitational quasi-normal modes of static R^2 Anti-de Sitter black holes

In this paper, we study the gravitational quasi-normal modes（QNMs） for a static R^2 black hole（BH） in Anti-de Sitter（AdS） spacetime. The corresponding master equation of odd parity is derived and the QNMs are evaluated by the Horowitz and Hubeny method. Meanwhile the stability of such BH is also discussed through the temporal evolution of the perturbation field. Here we mainly consider the coefficient λ, which is related to the radius of AdS black hole, on the QNMs of the R^2 AdS BH. The results show that the Re（ω） and ｜Im（ω）｜ of the QNMs increase together as ｜λ｜ increases for a given angular momentum number l. That indicates with a larger value of ｜λ｜ the corresponding R^2 AdS BH returns to stable much more quickly. The dynamic evolution of the perturbation field is consistent with the results derived by the Horowitz and Hubeny method. Since in the conformal field theory the QNMs can reflect its approach to equilibrium, so our related results could be referential to studies of the AdS/CFT conjecture. The relationship between λ and the properties of the static R^2 BH might be helpful for the development of R^2 gravitational theory.

P-V Criticality of a Modified BTZ Black Hole in 2 + 1 Dimensional Intrinsic Time Quantum Gravity

Intrinsic time quantum geometrodynamics is a formulation of quantum gravity naturally adapted to 3 + 1 dimensions. In this paper we construct its analogous 2 + 1 formulation, taking note of the mathematical structures which are preserved. We apply the resulting construction to convert the BTZ black hole metric to ITQG framework. We then modify the BTZ black hole in order to investigate the existence of the P-V criticality in ITQG theory.

Restudy of the stability problem of the Schwarzschild black hole

The stability of the Schwarzschild black hole is restudied in the Painlevé coordinates. Using the Painlevé time coordinate to define the initial time, we reconsider the odd perturbation and find that the Schwarzschild black hole in the Painlevé coordinates is unstable. The Painlevé metric in this paper corresponds to the white-hole-connected region of the Schwarzschild black hole （r 〉 2m） and the odd perturbation may be regarded as the angular perturbation. Therefore, the white-hole-connected region of the Schwarzschild black hole is unstable with respect to the rotating perturbation.

Teleparallel equivalent theory of (1+1)-dimensional gravity

A theory of （1＋1）-dimensional gravity is constructed on the basis of the teleparallel equivalent of general relativity. The fundamental field variables are the tetrad fields ei^μ and the gravity is attributed to the torsion. A dilatonic spherically symmetric exact solution of the gravitational field equations characterized by two parameters M and Q is derived. The energy associated with this solution is calculated using the two-dimensional gravitational energy- momentum formula.

Counting the Microstates at the Black Hole Horizon and the Immirzi Parameter of Loop Quantum Gravity

Motivated by Bekenstein’s original thought that led him to his famous area-entropy formula for a black hole and by our recent study regarding the black hole dynamics, we identify the appropriate microscopic degrees of freedom in loop quantum gravity that are responsible for the black hole entropy. We achieve consistent results by taking the j = 1/2 edges as dominant and by subjecting these edges to experience quantum fluctuations at the horizon. This also leads to a modification of the value of the Immirzi parameter in the SU(2) framework.

Hyperverse, 5-Dimensional Gravity and Multiverses as Nested Gogberashvili Shells

We consider the Hyperverse as a collection of multiverses in 5-dimensional spacetime with gravitational constant G. Each multiverse in our simplified model is a bouquet of nested spherical Gogberashvili shells. If gk is the gravitational constant of a thin shell Sk and εk, its thickness then G ~ εkgk. The physical universe is supposed to be one of those shells inside the local nested bouquet called Local Multiverse. We relate this construction to Robinson-Trautman metrics describing expanding spacetimes with spherical gravitational waves. Supermassive astronomical black holes, located at cores of elliptic/spiral galaxies, are also conjecturally described within this theory. Our constructions are equally consistent with the modern theory of cosmological coupling.

Critical behaviors of a(2+1)-dimensional black hole with a nonlinear electrodynamics source

On the basis of a charged BTZ black hole,we add an extra term in the metric function to describe the contribution from nonlinear electrodynamics.In this way we artificially construct a(2+1)-dimensional black hole in general relativity coupled with a nonlinear electrodynamics source.The thermodynamic quantities and Smarr formula are derived.It is found that this black hole has T-S criticality like that of an RN-Ad S black hole.Further modifying the metric function,we obtain a(2+1)-dimensional black hole possessing P-V critical behaviors similar to that of van der Waals fluid.To our knowledge,this is the first example of(2+1)-dimensional black holes having this kind of critical behavior.

一般圆对称2+1维时空的Hawking辐射

本文证明了在一般圆对称2＋1维动态时空中，采用广义乌龟坐标，可将KleinGordon方程的径向部分在事件视界附近化成标准的波动方程。

Novel Rotating Hairy Black Hole in (2 + 1) Dimensions

We present some novel rotating hairy black hole metric in （2 ＋ 1） dimensions, which is an exact solution to the field equations of the Einstein-scalar-AdS theory with a non-minimal coupling. The scalar potential is determined by the metric ansatz and consistency of the field equations and cannot be prescribed arbitrarily. In the simplified, critical ease, the scalar potential contains two independent constant parameters, which are respectively related to the mass and angular momentum of the black hole in a particular way. As long as the angular momentum does not vanish, the metric can have zero, one or two horizons. The case with no horizon is physically uninteresting because of the curvature singularity lying at the origin. We identify the necessary conditions for at least one horizon to be present in the solution, which imposes some bound on the mass-angular momentum ratio. For some particular choice of pararneters our solution degenerates into some previously known black hole solutions.

Dark sector production and baryogenesis from not quite black holes

Primordial black holes have been considered attractive dark matter candidates,whereas some of the predictions rely heavily on the near-horizon physics that remains to be tested experimentally.As a concrete alternative,thermal 2-2-holes closely resemble black holes without event horizons.Being a probable endpoint of gravitational collapse,they provide a solution to the information loss problem but also naturally result in stable remnants.Previously,we have considered primordial 2-2-hole remnants as dark matter.Owing to the strong constraints from a novel phenomenon associated with remnant mergers,only small remnants with mass approximate to the Planck mass can constitute all dark matter.In this paper,we examine the scenario in which the majority of dark matter consists of particles produced by the evaporation of primordial 2-2-holes,whereas the remnant contribution is secondary.The products with sufficiently light mass may contribute to the number of relativistic degrees of freedom in the early universe,which we also calculate.Moreover,2-2-hole evaporation can produce particles that are responsible for the baryon asymmetry.We observe that baryogenesis through direct B-violating decays or through leptogenesis can both be realized.Overall,the viable parameter space for the Planck remnant scenario is similar to that of primordial black holes with Planck remnants.However,heavier remnants result in different predictions,and the viable parameter space remains large even when the remnant abundance is small.

矢量粒子的隧穿辐射研究

在标量粒子、费米子的隧穿辐射研究基础上,讨论矢量粒子的隧穿辐射.矢量粒子的运动遵循Proca方程.利用WKB近似,研究矢量粒子在二维黑洞中的隧穿率,并通过隧穿率得到黑洞霍金温度.研究结果表明,黑洞温度同样可以通过矢量粒子的隧穿辐射得到.

二维黑洞热机及其效率研究

本文提出了一种二维黑洞热机模型,并研究了该热机的效率。发现其效率与黑洞辐射粒子前后的质量有关,此结果与以往文献所得出的结论一致。此外,还证明了黑洞辐射过程中最小半径的存在,并与先前的相关结论进行了比较和讨论。

(2+1)维动态黑洞的量子熵

在Tortoise坐标系中 ,利用brick wall模型研究了来源于标量场的 (2 +1 )维动态黑洞的量子熵 .结果表明 ,在视界附近的薄区域内标量场的熵与黑洞熵有相同结构 .特别是在静态情况下 。

Distinguishing the observational signatures of hot spots orbiting Reissner-Nordström spacetime

This paper investigates observable signatures of hot spots orbiting Reissner-Nordström(RN)black holes and naked singularities.For an RN black hole,we find two discernible lensing image tracks in time integrated images,capturing a complete orbit of hot spots and a image shadow within the critical curve where photons with a small impact parameter fall into the event horizon.Conversely,in RN singularities,additional image tracks can be found within the critical curve,originating from photons reflected by the infinitely high effective potential well.Moreover,we find incomplete and converging tracks from the time integrated images of hot spot orbiting RN singularities that have no photon sphere.The presence of these additional image tracks significantly influences temporal magnitudes at their local maxima,enabling us to differentiate between RN black holes and RN naked singularities.