scholarly journals Examining the weak cosmic censorship conjecture by gedanken experiments for an Einstein–Maxwell–Dilaton–Axion black hole

2020 ◽  
pp. 2050335
Author(s):  
Hai-Feng Ding ◽  
Xiang-Hua Zhai
Keyword(s):  
Black Hole ◽  
Cosmic Censorship ◽  
Second Order ◽  
Order Correction ◽  
Background Solution ◽  
Solution Parameters ◽  
Cosmic Censorship Conjecture

In the framework of the new version of the gedanken experiments proposed by Sorce and Wald, we investigate the weak cosmic censorship conjecture (WCCC) for an Einstein–Maxwell–Dilaton–Axion (EMDA) black hole. Our result shows that no violations of WCCC can occur with the increase of the background solution parameters for this near-extremal EMDA black hole when the second-order correction of the perturbations is taken into account. Namely, the near-extremal EMDA black hole cannot be over-charged or over-spun.

The effect of dark matter on the weak cosmic censorship conjecture in the extended space

2021 ◽  
pp. 2150207
Author(s):  
Zi-Yu Fu ◽  
Bao-Qi Zhang ◽  
Chuan-Yin Wang ◽  
Hui-Ling Li
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Second Law Of Thermodynamics ◽  
Cosmic Censorship ◽  
De Sitter ◽  
Extended Phase ◽  
Extended Space ◽  
Extreme Black Holes ◽  
Cosmic Censorship Conjecture

By analyzing the energy–momentum relationship of the absorbed fermions dropping into a Reissner–Nordstöm–anti-de Sitter black hole surrounded by dark matter, the laws of thermodynamic and weak cosmic censorship conjecture in the extended phase space are investigated. We find that the first law of thermodynamics is valid. However, the validity of the second law of thermodynamics depends on the density [Formula: see text] of the perfect fluid dark matter. In addition, we also find that when the fermions are absorbed, the structures of black hole surrounded by dark matter would not change. Therefore, weak cosmic censorship conjecture holds for the extreme black holes and the non-extreme black holes.

scholarly journals Magnetized Reissner–Nordström black hole restores cosmic censorship conjecture

2019 ◽  
Vol 49 ◽  
pp. 1960020 ◽  
Author(s):  
Sanjar Shaymatov
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Threshold Value ◽  
Cosmic Censorship ◽  
Black Hole Horizon ◽  
Charged Black Hole ◽  
The Magnetic Field ◽  
Cosmic Censorship Conjecture

We investigate the effect of magnetic field on the process of overcharging magnetized Reissner–Nordström black hole. It is well known that a four dimensional charged black hole could be overcharged. Contrary to this, we show that a magnetized charged black hole could not be overcharged beyond threshold value of the magnetic field. This occurs because the magnetic field does not allow for particle to reach black hole horizon. Thus magnetic field beyond its threshold value could restore the cosmic censorship conjecture.

scholarly journals A proof of the strong cosmic censorship conjecture

2020 ◽  
Vol 29 (14) ◽  
pp. 2042003
Author(s):  
Shahar Hod
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Second Law Of Thermodynamics ◽  
Cosmic Censorship ◽  
Necessary Condition ◽  
Deterministic Theory ◽  
Black Hole Spacetimes ◽  
Generalized Second Law ◽  
Strong Cosmic Censorship ◽  
Cosmic Censorship Conjecture

The Penrose strong cosmic censorship conjecture asserts that Cauchy horizons inside dynamically formed black holes are unstable to remnant matter fields that fall into the black holes. The physical importance of this conjecture stems from the fact that it provides a necessary condition for general relativity to be a truly deterministic theory of gravity. Determining the fate of the Penrose conjecture in nonasymptotically flat black hole spacetimes has been the focus of intense research efforts in recent years. In this paper, we provide a remarkably compact proof, which is based on Bekenstein’s generalized second law of thermodynamics, for the validity of the intriguing Penrose conjecture in physically realistic (dynamically formed) curved black hole spacetimes.

scholarly journals New version of the gedanken experiments to test the weak cosmic censorship in charged dilaton-Lifshitz black holes

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Jie Jiang ◽  
Ming Zhang
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Order Approximation ◽  
Energy Condition ◽  
Null Energy Condition ◽  
Cosmic Censorship ◽  
Second Order ◽  
Lifshitz Black Holes ◽  
Lifshitz Black Hole ◽  
Matter Fields

AbstractIn this paper, based on the new version of the gedanken experiments proposed by Sorce and Wald, we examine the weak cosmic censorship in the perturbation process of accreting matter fields for the charged dilaton-Lifshitz black holes. In the investigation, we assume that the black hole is perturbed by some extra matter source satisfied the null energy condition and ultimately settle down to a static charged dilaton-Lifshitz black hole in the asymptotic future. Then, after applying the Noether charge method, we derive the first-order and second-order perturbation inequalities of the perturbation matter fields. As a result, we find that the nearly extremal charged dilaton-Lifshitz black hole cannot be destroyed under the second-order approximation of perturbation. This result implies that the weak cosmic censorship conjecture might be a general feature of the Einstein gravity, and it is independent of the asymptotic behaviors of the black holes.

scholarly journals Weak cosmic censorship conjecture for a Kerr-Taub-NUT black hole with a test scalar field and particle

2020 ◽  
Vol 101 (6) ◽  
Author(s):  
Si-Jiang Yang ◽  
Jing Chen ◽  
Jun-Jie Wan ◽  
Shao-Wen Wei ◽  
Yu-Xiao Liu
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Cosmic Censorship ◽  
Cosmic Censorship Conjecture

GRAVITATIONAL COLLAPSE OF A SELF-INTERACTING SCALAR FIELD

2007 ◽  
Vol 22 (01) ◽  
pp. 65-74 ◽  
Author(s):  
RITUPARNO GOSWAMI ◽  
PANKAJ S. JOSHI
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Gravitational Collapse ◽  
Energy Condition ◽  
Dynamical Evolution ◽  
Naked Singularity ◽  
Cosmic Censorship ◽  
Weak Energy Condition ◽  
Scalar Field Models ◽  
Cosmic Censorship Conjecture

We construct and study here a class of collapsing scalar field models with a nonzero potential. The weak energy condition is satisfied by the collapsing configuration and it is shown that the end state of collapse could be either a black hole or a naked singularity. It is seen that physically it is the rate of collapse that governs these outcomes of the dynamical evolution. The implications for the cosmic censorship conjecture are discussed.

scholarly journals The weak cosmic censorship conjecture may be violated

2020 ◽  
Author(s):  
Wen-Xiang Chen
Keyword(s):  
Black Hole ◽  
Wave Function ◽  
Boundary Conditions ◽  
Cosmic Censorship ◽  
Traditional Theory ◽  
Schwarzschild Black Hole ◽  
Entropy Reduction ◽  
Set Up ◽  
Coupled Wave ◽  
Cosmic Censorship Conjecture

According to traditional theory, the Schwarzschild black hole does not produce superradiation. If the boundary conditions are set up in advance, this possibility will be combined with the boson-coupled wave function in the Schwarzschild black hole, where the incident boson will have a mirrored mass, so even the Schwarzschild black hole can generate superradiation phenomena.Recently, an article of mine obtained interesting results about the Schwarzschild black hole can generate superradiation phenomena. The result contains some conclusions that violate the "no-hair theorem". We know that the phenomenon of black hole superradiation is a process of entropy reduction I found that the weak cosmic censorship conjecture may be violated.

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