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 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

scholarly journals Weak cosmic censorship conjecture in Kerr black holes of modified gravity

2019 ◽  
Vol 34 (05) ◽  
pp. 1950037 ◽  
Author(s):  
Bin Liang ◽  
Shao-Wen Wei ◽  
Yu-Xiao Liu
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Lower Energy ◽  
Energy Gap ◽  
Naked Singularity ◽  
Cosmic Censorship ◽  
Point Particle ◽  
Adiabatic Process ◽  
Energy Bounds ◽  
Cosmic Censorship Conjecture

By neglecting the effects of self-force and radiation, we investigate the possibility of destroying the Kerr-MOG black hole through the point particle absorption process. Using the instability of event horizon and equation of particle motion, we get the upper and lower energy bounds allowed for a matter particle to produce the naked singularity. We find that the energy gap always exists between the upper and lower energy bounds for both extremal and near-extremal black holes, which means some tailored particles can actually lead to the violation of the weak cosmic censorship conjecture. However, when considering the effect of the adiabatic process, the result shows that the Kerr-MOG black hole gets more stable instead of a naked singularity, and thus the weak cosmic censorship conjecture can be restored at some level.

Static axisymmetric discs and gravitational collapse

1987 ◽  
Vol 413 (1844) ◽  
pp. 251-262 ◽  
Keyword(s):  
Gravitational Collapse ◽  
Energy Condition ◽  
Naked Singularity ◽  
Cosmic Censorship ◽  
Field Equations ◽  
Exterior Field ◽  
Thin Disc ◽  
Cosmic Censorship Hypothesis ◽  
Hoop Conjecture ◽  
Vacuum Solutions

Regular static axisymmetric vacuum solutions of Einstein’s field equations representing the exterior field of a finite thin disc are found. These are used to describe the slow collapse of a disc-like object. If no conditions are placed on the matter, a naked singularity is formed and the cosmic censorship hypothesis would be violated. Imposition of the weak energy condition, however, prevents slow collapse to a singularity and preserves the validity of this hypothesis. The validity of the hoop conjecture is also discussed.

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.

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.

scholarly journals Gravitational Collapse

1974 ◽  
Vol 64 ◽  
pp. 82-91 ◽  
Author(s):  
R. Penrose
Keyword(s):  
Black Hole ◽  
Gravitational Collapse ◽  
Naked Singularity ◽  
Cosmic Censorship ◽  
Space Time ◽  
Local Version ◽  
Time Singularities ◽  
Standard Picture ◽  
Cosmic Censorship Hypothesis ◽  
Definition Of

In the standard picture of gravitational collapse to a black hole, a key role is played by the hypothesis of cosmic censorship – according to which no naked space-time singularities can result from any collapse. A precise definition of a naked singularity is given here which leads to a strong ‘local’ version of the cosmic censorship hypothesis. This is equivalent to the proposition that a Cauchy hypersurface exits for the space-time. The principle that the surface area of a black hole can never decrease with time is presented in a new and simplified form which generalizes the earlier statements. A discussion of the relevance of recent work to the naked singularity problem is also given.

scholarly journals Testing the weak cosmic censorship conjecture in torus-like black hole under charged scalar field

2020 ◽  
Vol 29 (12) ◽  
pp. 2050078
Author(s):  
Wei Hong ◽  
Benrong Mu ◽  
Jun Tao
Keyword(s):  
Black Hole ◽  
Phase Space ◽  
Scalar Field ◽  
Second Law Of Thermodynamics ◽  
Cosmic Censorship ◽  
Second Law ◽  
Complex Scalar ◽  
Charged Scalar ◽  
First Law Of Thermodynamics ◽  
Cosmic Censorship Conjecture

We investigate weak cosmic censorship conjecture in charged torus-like black hole by the complex scalar field scattering. Using the relation between the conserved quantities of a black hole and the scalar field, we can calculate the change of the energy and charge within the infinitesimal time. The change of the enthalpy is connected to the change of energy, then we use those results to test whether the first law, the second law as well as the weak cosmic censorship conjecture are valid. In the normal phase–space, the first law of thermodynamics and the weak cosmic censorship conjecture are valid, and the second law of thermodynamics is not violated. For the specific black hole under scalar field scattering we consider, in the extended phase–space, the first law of thermodynamics and the weak cosmic censorship conjecture are valid. However, the second law of thermodynamics is violated when the black hole’s initial charge reaches a certain value.

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