scholarly journals Black-Hole No-Hair Theorems for a Positive Cosmological Constant

2007 ◽  
Vol 99 (20) ◽  
Author(s):  
Sourav Bhattacharya ◽  
Amitabha Lahiri
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Positive Cosmological Constant

scholarly journals Thermodynamics of Schwarzschild–Beltrami–de Sitter black hole

2017 ◽  
Vol 32 (27) ◽  
pp. 1750146 ◽  
Author(s):  
Hang Liu ◽  
Xin-He Meng
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Spherical Symmetry ◽  
Inertial Force ◽  
De Sitter ◽  
Positive Cosmological Constant ◽  
First Law Of Thermodynamics ◽  
Thermodynamical Properties ◽  
Killing Horizon ◽  
Entropy Bound

In this paper, we investigate the thermodynamical properties of Schwarzschild–Beltrami–de Sitter (S–BdS) black hole introduced by Yan et al. in 2013 by introducing inertial Beltrami coordinates to traditional non-inertial Schwarzschild–de Sitter (S–dS) metric which is the exact static spherical symmetry solution of Einstein equation with a positive cosmological constant [Formula: see text]. Based on this new metric, we compute entropy on all horizons and we give the entropy bound of the black hole. Hawking temperatures are calculated by considering a perturbation to entropy relations due to that the spacetime described by these inertial coordinates is no longer a stationary spacetime in which surface gravity related to Hawking temperature is defined well on killing horizon. We also get the Smarr relations and the first law of thermodynamics. We find that the S–BdS black hole seems to have similar thermodynamical properties to S–dS black hole in the comparison between their corresponding thermodynamical quantities, although the new black hole metric is described by inertial coordinates which exclude the effects of inertial force.

scholarly journals Two dimensional nearly de Sitter gravity

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Juan Maldacena ◽  
Gustavo J. Turiaci ◽  
Zhenbin Yang
Keyword(s):  
Black Hole ◽  
Perturbation Theory ◽  
Cosmological Constant ◽  
Extremal Black Hole ◽  
Probability Measures ◽  
Two Dimensional ◽  
De Sitter ◽  
Positive Cosmological Constant ◽  
Boundary Mode ◽  
Dimensional Gravity

Abstract We study some aspects of the de Sitter version of Jackiw-Teitelboim gravity. Though we do not have propagating gravitons, we have a boundary mode when we compute observables with a fixed dilaton and metric at the boundary. We compute the no-boundary wavefunctions and probability measures to all orders in perturbation theory. We also discuss contributions from different topologies, borrowing recent results by Saad, Shenker and Stanford. We discuss how the boundary mode leads to gravitational corrections to cosmological observables when we add matter. Finally, starting from a four dimensional gravity theory with a positive cosmological constant, we consider a nearly extremal black hole and argue that some observables are dominated by the two dimensional nearly de Sitter gravity dynamics.

scholarly journals Electromagnetic perturbations of a de Sitter black hole in massive gravity

2017 ◽  
Vol 26 (09) ◽  
pp. 1750100 ◽  
Author(s):  
Sharmanthie Fernando ◽  
Amanda Manning
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Cross Sections ◽  
High Frequency ◽  
Quasinormal Modes ◽  
Massive Gravity ◽  
De Sitter ◽  
Positive Cosmological Constant ◽  
Frequency Limit ◽  
Electromagnetic Perturbations

The main purpose of this paper is to study quasinormal modes (QNM) of a black hole in massive gravity with a positive cosmological constant due to electromagnetic perturbations. A detailed study of the QNM frequencies for the electromagnetic field is done by varying the parameters of the theory such as the mass, scalar charge, cosmological constant, and the spherical harmonic index. We have employed the sixth-order WKB approximation to calculate the QNM frequencies. The electromagnetic potential for the near extreme massive gravity de Sitter black hole is approximated with the Pöschl–Teller potential to obtain exact frequencies. The null geodesics of the black hole in massive gravity is employed to describe the absorption cross-sections at high-frequency limit.

scholarly journals BLACK-HOLE HAVING ELECTRIC HAIRS FOR POSITIVE COSMOLOGICAL CONSTANT Λ>0 ON A COSMIC HORIZON SCALE ~1/√Λ

2021 ◽  
pp. 281-282
Author(s):  
Sanjeevan Singha Roy ◽  
Aruna Harikant ◽  
Deep Bhattacharjee
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Maximum Density ◽  
Black Hole Horizon ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Positive Cosmological Constant ◽  
Black Hole Singularity ◽  
Stress Energy ◽  
Limit Stress

This paper is a technical review for a more deliberate paper (Bhattacharya & Lahiri, 2007) where it has been shown that on a positive cosmological scale with Λ>0 having a cosmic horizon scale ~1/√Λ, there exists the soft electric hairs for the solution having the T_00 components of the stress-energy tensor T_μν i.e., ρ=0 on black hole horizon B_H having the maximum density at black hole singularity B_S where cosmic horizon C_H and black hole horizon B_H has only been considered. KEYWORDS: Black Hole – Cosmic Horizon – TOV Limit – Stress-Energy Tensor – Positive Cosmological Constant

scholarly journals SPACE TIME FOAM

2002 ◽  
Vol 17 (06n07) ◽  
pp. 829-832 ◽  
Author(s):  
REMO GARATTINI
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Ground State ◽  
Casimir Energy ◽  
Space Time ◽  
De Sitter ◽  
Schwarzschild Black Hole ◽  
Positive Cosmological Constant ◽  
Hole Transition

In the context of a model of space-time foam, made by N wormholes we discuss the possibility of having a foam formed by different configurations. An equivalence between Schwarzschild and Schwarzschild-Anti-de Sitter wormholes in terms of Casimir energy is shown. An argument to discriminate which configuration could represent a foamy vacuum coming from Schwarzschild black hole transition frequencies is used. The case of a positive cosmological constant is also discussed. Finally, a discussion involving charged wormholes leads to the conclusion that they cannot be used to represent a ground state of the foamy type.

scholarly journals SKYRMION AND SKYRME-BLACK HOLES IN de SITTER SPACETIME

2006 ◽  
Vol 21 (27) ◽  
pp. 2043-2054 ◽  
Author(s):  
YVES BRIHAYE ◽  
TERENCE DELSATE
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Cosmological Constant ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Positive Cosmological Constant ◽  
Asymptotically Flat ◽  
Sitter Spacetime ◽  
Black Hole Solutions

Numerical arguments are presented for the existence of regular and black hole solutions of the Einstein–Skyrme equations with a positive cosmological constant. These classical configurations approach asymptotically the de Sitter spacetime. The main properties of the solutions and the differences with respect to the asymptotically flat ones are discussed. In particular our results suggest that, for a positive cosmological constant, the mass evaluated as timelike infinity in infinite. Special emphasis is set to de Sitter black holes Skyrmions which display two horizons.

GRAVITATIONAL PERFECT FLUID COLLAPSE WITH COSMOLOGICAL CONSTANT

2007 ◽  
Vol 22 (20) ◽  
pp. 1493-1502 ◽  
Author(s):  
M. SHARIF ◽  
ZAHID AHMAD
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Perfect Fluid ◽  
Physical Significance ◽  
Spherically Symmetric ◽  
Positive Cosmological Constant ◽  
Matching Conditions ◽  
Apparent Horizons ◽  
Dust Case

In this paper, the effect of a positive cosmological constant on spherically symmetric collapse with perfect fluid has been investigated. The matching conditions between static exterior and non-static interior spacetimes are given in the presence of a cosmological constant. We also study the apparent horizons and their physical significance. It is concluded that the cosmological constant slows down the collapse of matter and hence limit the size of the black hole. This analysis gives the generalization of the dust case to the perfect fluid. We recover the results of the dust case for p = 0.

scholarly journals Black hole spontaneous scalarisation with a positive cosmological constant

2020 ◽  
Vol 802 ◽  
pp. 135269 ◽  
Author(s):  
Yves Brihaye ◽  
Carlos Herdeiro ◽  
Eugen Radu
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Positive Cosmological Constant

scholarly journals Neutral signature gauged supergravity solutions

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
J. Gutowski ◽  
W. A. Sabra
Keyword(s):  
Cosmological Constant ◽  
Geometric Structure ◽  
Base Space ◽  
Killing Spinor ◽  
Positive Cosmological Constant ◽  
3 Dimensional

Abstract We classify all supersymmetric solutions of minimal D = 4 gauged supergravity with (2) signature and a positive cosmological constant which admit exactly one Killing spinor. This classification produces a geometric structure which is more general than that found for previous classifications of N = 2 supersymmetric solutions of this theory. We illustrate how the N = 2 solutions which consist of a fibration over a 3-dimensional Lorentzian Gauduchon-Tod base space can be written in terms of this more generic geometric structure.

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