On gravitational collapse and cosmic censorship for collisionless matter

2014 ◽  
Vol 11 (02) ◽  
pp. 1460002 ◽  
Author(s):  
Håkan Andréasson
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Gravitational Collapse ◽  
Open Problem ◽  
Present Status ◽  
Spherical Symmetry ◽  
Cosmic Censorship ◽  
Classical General Relativity ◽  
Matter Model ◽  
Cosmic Censorship Conjecture

The weak cosmic censorship conjecture is a central open problem in classical general relativity. Under the assumption of spherical symmetry, Christodoulou has investigated the conjecture for two different matter models; a scalar field and dust. He has shown that the conjecture holds true for a scalar field but that it is violated in the case of dust. The outcome of the conjecture is thus sensitive to which model is chosen to describe matter. Neither a scalar field nor dust are realistic matter models. Collisionless matter, or Vlasov matter, is a simple matter model but can be considered to be realistic in the sense that it is used by astrophysicists. The present status on the weak cosmic censorship conjecture for the Einstein–Vlasov system is reviewed here.

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 Space–time singularities and cosmic censorship conjecture: A Review with some thoughts

2020 ◽  
Vol 35 (14) ◽  
pp. 2030007 ◽  
Author(s):  
Yen Chin Ong
Keyword(s):  
General Relativity ◽  
Short Review ◽  
Big Bang ◽  
Cosmic Censorship ◽  
Space Time ◽  
Singularity Theorems ◽  
Time Singularities ◽  
The One ◽  
The Big Bang ◽  
Cosmic Censorship Conjecture

The singularity theorems of Hawking and Penrose tell us that singularities are common place in general relativity. Singularities not only occur at the beginning of the Universe at the Big Bang, but also in complete gravitational collapses that result in the formation of black holes. If singularities — except the one at the Big Bang — ever become “naked,” i.e. not shrouded by black hole horizons, then it is expected that problems would arise and render general relativity indeterministic. For this reason, Penrose proposed the cosmic censorship conjecture, which states that singularities should never be naked. Various counterexamples to the conjecture have since been discovered, but it is still not clear under which kind of physical processes one can expect violation of the conjecture. In this short review, I briefly examine some progresses in space–time singularities and cosmic censorship conjecture. In particular, I shall discuss why we should still care about the conjecture, and whether we should be worried about some of the counterexamples. This is not meant to be a comprehensive review, but rather to give an introduction to the subject, which has recently seen an increase of interest.

scholarly journals Strong cosmic censorship under quasinormal modes of non-minimally coupled massive scalar field

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
Bogeun Gwak
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Decay Rate ◽  
Small Mass ◽  
Cosmic Censorship ◽  
Massive Scalar ◽  
De Sitter ◽  
Massive Scalar Field ◽  
Strong Cosmic Censorship ◽  
Cosmic Censorship Conjecture

Abstract We investigate the strong cosmic censorship conjecture in lukewarm Reissner–Nordström–de Sitter black holes (and Martínez–Troncoso–Zanelli black holes) using the quasinormal resonance of non-minimally coupled massive scalar field. The strong cosmic censorship conjecture is closely related to the stability of the Cauchy horizon governed by the decay rate of the dominant quasinormal mode. Here, dominant modes are obtained in the limits of small and large mass black holes. Then, we connect the modes by using the WKB approximation. In our analysis, the strong cosmic censorship conjecture is valid except in the range of the small-mass limit, in which the dominant mode can be assumed to be that of the de Sitter spacetime. Particularly, the coupling constant and mass of the scalar field determine the decay rate in the small mass range. Therefore, the validity of the strong cosmic censorship conjecture depends on the characteristics of the scalar field.

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

Lemaitre–Tolman–Bondi dust cloud collapse in Brans–Dicke gravity

2014 ◽  
Vol 29 (35) ◽  
pp. 1450192 ◽  
Author(s):  
Muhammad Sharif ◽  
Rubab Manzoor
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Scalar Field ◽  
Perfect Fluid ◽  
Gravitational Collapse ◽  
Potential Field ◽  
Dust Cloud ◽  
Energy Conditions ◽  
Different Types

This paper investigates the phenomenon of gravitational collapse of Lemaitre–Tolman–Bondi (LTB) model in the presence of Brans–Dicke (BD) scalar field with nonzero potential field. We find a class of solutions by taking perfect fluid as well as scalar field and check the validity of weak energy conditions. It turns out that two different types of singularities are formed in the presence of scalar field. We conclude that the end state of gravitational collapse turns out to be a black hole (BH) contrary to general relativity (GR).

New Exact Vacuum Solutions in Brans–Dicke Theory

1997 ◽  
Vol 12 (25) ◽  
pp. 1865-1870 ◽  
Author(s):  
Luis O. Pimentel
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Initial Data ◽  
Cosmological Model ◽  
Exact Solutions ◽  
Spherical Symmetry ◽  
Physical System ◽  
Special Value ◽  
Isotropic Cosmological Model ◽  
Vacuum Solutions

A family of exact solutions to vacuum Brans–Dicke theory with spherical symmetry is found. In the limit of large ω this family reduces to the solutions obtained in general relativity with a scalar field. The solutions show curvature singularities for all times, therefore they do not represent the gravitational collapse of a physical system with regular initial data in the theory. One would like to interpret it as an inhomogeneous dynamical cosmology, but the lack of a regular spacelike slice forbids it. For a special value of an integration constant we have an isotropic cosmological model without the problems mentioned above.

Finding the Singularity of a Black Hole: Cosmic Censorship Conjecture

2020 ◽  
Vol 29 (12) ◽  
pp. 10-16
Author(s):  
Bogeun GWAK
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Mass Density ◽  
Energy Condition ◽  
Deep Understanding ◽  
Compact Object ◽  
Null Energy Condition ◽  
Cosmic Censorship ◽  
Weak Version ◽  
Cosmic Censorship Conjecture

According to the singularity theorem, a curvature singularity can be formed in a gravitational collapse under the null energy condition. Eventually, the singularity possesses sufficient mass density for the horizon to appear, and the compact object thereby evolves into a black hole. Hence, on the basis of general relativity, the singularity must be located at the center of the black hole. Our curiosity begins here: can we see the singularity? To answer this question, the cosmic censorship conjecture comes into play. That conjecture, which was originally proposed by Penrose, has two versions. The weak version states that a static observer located outside the black hole cannot see the singularity. Furthermore, the strong version states that no observers can see the singularity. Studies regarding the cosmic censorship conjecture are still ongoing, and evidently, its validation requires a deep understanding of the theory of gravity, including general relativity. Herein, we review the progress of studies associated with the weak and the strong cosmic censorship conjectures. Furthermore, we briefly describe the Penrose process for extracting energy from a black hole.

scholarly journals Critical behavior in the gravitational collapse of a scalar field with angular momentum in spherical symmetry

2007 ◽  
Vol 76 (12) ◽  
Author(s):  
Ignacio (Iñaki) Olabarrieta ◽  
Jason F. Ventrella ◽  
Matthew W. Choptuik ◽  
William G. Unruh
Keyword(s):  
Angular Momentum ◽  
Scalar Field ◽  
Gravitational Collapse ◽  
Critical Behavior ◽  
Spherical Symmetry
Sign in / Sign up

Export Citation Format

Share Document