Invited talk presented at the 2009 Joint Annual Conference of the National Society of Black Physicists and the National Society of Hispanic Physicists, Feb. 10-14, Nashville, Tennessee
Dynamic space-times, especially those manifesting horizons, provide useful laboratories for examining how macroscopic quantum behaviors consistently co-generate gravitational phenomena. For this reason, the behaviors and large-scale causal structures of spatially coherent dynamic black holes will be explored in this presentation. Geodesic motions on an evaporating black hole will also be presented. Research recently completed with Beth Brown, including her final Penrose diagram for an accreting black hole, will be presented.
We offer a mathematically rigorous basis for the widely held suspicion that full black hole evaporation is in tension with predictability. Based on conditions expressing the global causal structure of evaporating black hole spacetimes, we prove two theorems in Lorentzian geometry showing that such spacetimes either fail to be causally simple or fail to be causally continuous. These theorems, when combined with recent results \cite{AM} on the causal structure of spacetimes with timelike boundary, bear significantly on the question of whether these spacetimes permit for a predictable evolution.
A precise definition of a black hole has long been absent in causal set theory. I first show that the local finiteness of the theory cannot be interpreted as a complete discretization condition, and the theory still admits continua, which I call singular anti-chains. After providing a couple of suggestive calculations from general relativity to support the argument that a singular anti-chain behaves like a causal singularity in a space-time, I propose a definition of a causal set black hole based on a singular anti-chain. The paper concludes with brief discussions of questions that causal set …
Accelerating black holes are described by the so-called C-metric. In this work, we analyse the causal structure of such black holes by using null geodesics. We construct explicitly the relevant Penrose diagrams. First, we recover well-known results associated with the sub-accelerating black holes. Then, we extend the study to the super-accelerating case, in which an additional essential singularity appears. In addition, we consider accelerating black holes with negative masses. We show that they are equivalent to the geometry described by the black hole metric beyond conformal infinity. We com…
The causal structure of the recent loop quantum gravity black hole collapse model [1] is analysed. As the spacetime is only approximately diffeomorphism invariant up to powers of $\hbar$, it is not straight forwardly possible to find global conformally compactified coordinates and to construct the Penrose diagram. Therefore, radial in- and outgoing light rays are studied to extract the causal features and sketch a causal diagram. It was found that the eternal metric [2], which is the vacuum solution of the collapse model, has a causal horizon. However, in the collapsing case light rays travel …
We study charged black hole solutions in 4-dimensional (4D) Einstein-Gauss-Bonnet-Maxwell theory to the linearized perturbation level. We first compute the shear viscosity to entropy density ratio. We then demonstrate how bulk causal structure analysis imposes a upper bound on the Gauss-Bonnet coupling constant in the AdS space. Causality constrains the value of Gauss-Bonnet coupling constant $α_{GB}$ to be bounded by $α_{GB}\leq 0$ as $D\rightarrow 4$.
We consider black hole in Einstein-Gauss-Bonnet(EGB) gravity in a dynamical setup and also the stationary black hole in recently discovered\cite{Glavan} $4$-dimensional novel Einstein-Gauss-Bonnet gravity. For dynamical EGB black hole in completely local settings we calculate the temperature associated with the horizon. For the stationary black hole in $4$-dimensional novel EGB theory we explore the thermodynamic properties including calculation of temperature and entropy.
Inverse Reconstruction of Causal Nonlinear Electrodynamics: Functional Families, Spectral Constraints, and Single-Horizon Black Holes
Institute of Physics and Astronomy, Faculty of Sciences, Universidad de Valparaíso（瓦尔帕莱索大学理学院物理与天文学研究所）；Center for Research in Space Sciences and Theoretical Physics (CICEF), Universidad Central de Chile（智利中央大学空间科学与理论物理研究中心）
The shadow of a black hole can be one of the strong observational evidences for stationary black holes. If we see shadows at the center of galaxies, we would say whether the observed compact objects are black holes. In this paper, we consider a formula for the contour of a shadow in an asymptotically-flat, stationary, and axisymmetric black hole spacetime. We show that the formula is useful for obtaining the contour of the shadow of several black holes such as the Kerr-Newman black hole and rotating regular black holes. Using the formula, we can obtain new examples of the contour of the shadow…
In this work, motivated by the fact that higher-dimensional theories predict the existence of black holes which differ from their four-dimensional counterpart, we analyse the geodesics and black hole shadow cast by a general non-extremal five-dimensional black hole. The system under consideration corresponds to the Chong-Cvetič-Lü-Pope (Phys. Rev.Lett.{\bf 95}, 161301 (2005)), which has the Myers--Perry black hole as a limit.
Causal Space-Time Structure and non-Hausdorff Extension of Schwarzschild Black Hole Interior
Landau Phystech-School, Moscow Institute of Physics and Technology（兰道物理技术学院，莫斯科物理技术学院）；Institute for High Energy Physics of National Research Centre "Kurchatov Institute"（库尔恰托夫国家研究中心高能物理研究所）
By throwing a test charged particle into a Reissner-Nordstrom (RN) black hole, we test the validity of the first and second laws of thermodynamics and weak cosmic censorship conjecture (WCCC) with two types of boundary conditions, i.e., the asymptotically anti-de Sitter (AdS) space and a Dirichlet cavity wall placed in the asymptotically at space. For the RN-AdS black hole, the second law of thermodynamics is satisfied, and the WCCC is violated for both extremal and nearextremal black holes. For the RN black hole in a cavity, the entropy can either increase or decrease depending on the change …
The superradiant stability of higher dimensional non-extremal Reissner-Nordstrom black hole under charged massive scalar perturbation is analytically studied. We extend our previous studies of four- and five-dimensional non-extremal Reissner-Nordstrom black hole cases to six-dimensional case. By analyzing the derivative of the effective potential with an analytical method, we find that no potential well exists outside the outer horizon of the black hole for the superradiant scalar modes. This means that there is no black hole bomb for the system consisting of six-dimensional Reissner-Nordstrom…
We introduce three approaches to generate curvature invariants that transform covariantly under a conformal transformation of a four dimensional spacetime. For any black hole conformally related to a stationary black hole, we show how a set of conformally covariant invariants can be combined to produce a conformally covariant invariant that detects the event horizon of the conformally related black hole. As an application we consider the rotating dynamical black holes conformally related to the Kerr-NUT-(Anti)-de Sitter spacetimes and construct an invariant that detects the conformal Killing h…
The Event Horizon Telescope, a global submillimeter wavelength very long baseline interferometry array, produced the first image of supermassive black hole M87* showing a ring of diameter $θ_d= 42\pm 3\,μ$as, inferred a black hole mass of $M=(6.5 \pm 0.7) \times 10^9 M_\odot $ and allowed us to investigate the nature of strong-field gravity. The observed image is consistent with the shadow of a Kerr black hole, which according to the Kerr hypothesis describes the background spacetimes of all astrophysical black holes. The hypothesis, a strong-field prediction of general relativity, may be viol…
In this work, starting from a spherically symmetric scale--dependent black hole, a rotating solution is obtained by following the Newman--Janis algorithm without complexification. Besides studying the horizon, the static conditions and causality issues of the rotating solution, we get and discuss the shape of its shadow.
We investigate $4D$ Einstein-Gauss-bonnet gravity coupled to exponential electrodynamics in AdS background and found a static, spherically symmetric exact black hole solution. The horizon structure of black hole is discussed. Treating the cosmological constant as pressure, we drive first law of black hole thermodynamics in extended phase space. We compute the electrostatic potential and vacuum polarization of the black hole. To study local thermodynamical stability specific heat of the black hole is computed. Finally, we study Helmholtz free energy to analyse the global stability of black hole…
The superradiant stability of asymptotically flat D-dimensional extremal Reissner-Nordstrom black holes under charged massive scalar perturbation is analytically studied. Recently, an analytical method has been proposed by the author and used to prove that five and six-dimensional extremal Reissner-Nordstrom black holes are superradiantly stable under charged massive scalar perturbation. We apply this analytical method in the D-dimensional extremal Reissner-Nordstrom black hole cases and prove that the D-dimensional Reissner-Nordstrom black holes are all superradiantly stable under charged mas…
