scholarly journals SINGULARITY IN GRAVITATIONAL COLLAPSE OF PLANE SYMMETRIC CHARGED VAIDYA SPACETIME

2010 ◽  
Vol 25 (33) ◽  
pp. 2831-2836 ◽  
Author(s):  
M. SHARIF ◽  
AISHA SIDDIQA
Keyword(s):  
Gravitational Collapse ◽  
Energy Condition ◽  
Cosmic Censorship ◽  
Final Outcome ◽  
Curvature Singularity ◽  
Field Equations ◽  
Plane Symmetric ◽  
Counter Example ◽  
Cosmic Censorship Hypothesis ◽  
Strong Curvature

We study the final outcome of gravitational collapse resulting from the plane symmetric charged Vaidya spacetime. Using the field equations, we show that the weak energy condition is always satisfied by collapsing fluid. It is found that the singularity formed is naked. The strength of singularity is also investigated by using Nolan's method. This turns out to be a strong curvature singularity in Tipler's sense and hence provides a counter example to the cosmic censorship hypothesis.

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.

HIGHER DIMENSIONAL CHARGED NULL FLUID COLLAPSE AND COSMIC CENSORSHIP

2002 ◽  
Vol 11 (02) ◽  
pp. 237-244 ◽  
Author(s):  
S. G. GHOSH ◽  
R. V. SARAYKAR
Keyword(s):  
Black Holes ◽  
Energy Condition ◽  
Cosmic Censorship ◽  
Final Outcome ◽  
Spherically Symmetric ◽  
Curvature Singularity ◽  
Naked Singularities ◽  
Dimensional Spacetime ◽  
Higher Dimensional ◽  
Strong Curvature

We analyze here the spherically symmetric collapse of a charged null fluid in a higher dimensional spacetime. Both naked singularities and black holes are shown to be developing as final outcome of the collapse. A relationship between weak energy condition and occurrence of strong curvature singularity is pointed out.

scholarly journals GENERALIZED STRONG CURVATURE SINGULARITIES AND COSMIC CENSORSHIP

2002 ◽  
Vol 17 (07) ◽  
pp. 387-397 ◽  
Author(s):  
WIESŁAW RUDNICKI ◽  
ROBERT J. BUDZYŃSKI ◽  
WITOLD KONDRACKI
Keyword(s):  
Causal Structure ◽  
Cosmic Censorship ◽  
Single Type ◽  
Curvature Singularity ◽  
Cosmic Censorship Hypothesis ◽  
Definition Of ◽  
Strong Curvature

A new definition of a strong curvature singularity is proposed. This definition is motivated by the definitions given by Tipler and Królak, but is significantly different and more general. All causal geodesics terminating at these new singularities, which we call generalized strong curvature singularities, are classified into three possible types; the classification is based on certain relations between the causal structure and the curvature strength of the singularities. A cosmic censorship theorem is formulated and proved which shows that only one class of generalized strong curvature singularities, corresponding to a single type of geodesics according to our classification, can be naked. Implications of this result for the cosmic censorship hypothesis are indicated.

scholarly journals GRAVITATIONAL COLLAPSE OF PERFECT FLUID IN SELF-SIMILAR HIGHER DIMENSIONAL SPACE–TIMES

2003 ◽  
Vol 12 (05) ◽  
pp. 913-924 ◽  
Author(s):  
S. G. GHOSH ◽  
D. W. DESHKAR
Keyword(s):  
Perfect Fluid ◽  
Gravitational Collapse ◽  
Dimensional Space ◽  
Energy Condition ◽  
Cosmic Censorship ◽  
Naked Singularities ◽  
Four Dimensions ◽  
Higher Dimensional ◽  
Self Similar ◽  
Strong Curvature

We investigate the occurrence and nature of naked singularities in the gravitational collapse of an adiabatic perfect fluid in self-similar higher dimensional space–times. It is shown that strong curvature naked singularities could occur if the weak energy condition holds. Its implication for cosmic censorship conjecture is discussed. Known results of analogous studies in four dimensions can be recovered.

scholarly journals HIGHER DIMENSIONAL INHOMOGENEOUS DUST COLLAPSE AND COSMIC CENSORSHIP

2002 ◽  
Vol 17 (20) ◽  
pp. 2747-2747
Author(s):  
A. BEESHAM
Keyword(s):  
Black Holes ◽  
Cosmic Censorship ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Naked Singularities ◽  
Singularity Theorems ◽  
Sitter Spacetime ◽  
Higher Dimensional ◽  
Cosmic Censorship Hypothesis ◽  
Strong Curvature

The singularity theorems of general relativity predict that gravitational collapse finally ends up in a spacetime singularity1. The cosmic censorship hypothesis (CCH) states that such a singularity is covered by an event horizon2. Despite much effort, there is no rigorous formulation or proof of the CCH. In view of this, examples that appear to violate the CCH and lead to naked singularities, in which non-spacelike curves can emerge, rather than black holes, are important to shed more light on the issue. We have studied several collapse scenarios which can lead to both situations3. In the case of the Vaidya-de Sitter spacetime4, we have shown that the naked singularities that arise are of the strong curvature type. Both types of singularities can also arise in higher dimensional Vaidya and Tolman-Bondi spacetimes, but black holes are favoured in some sense by the higher dimensions. The charged Vaidya-de Sitter spacetime also exhibits both types of singularities5.

INHOMOGENEOUS DUST COLLAPSE WITH COSMOLOGICAL CONSTANT

2005 ◽  
Vol 14 (03n04) ◽  
pp. 707-715 ◽  
Author(s):  
S. G. GHOSH
Keyword(s):  
Cosmological Constant ◽  
Gravitational Collapse ◽  
Dust Cloud ◽  
Cosmic Censorship ◽  
Space Time ◽  
De Sitter ◽  
Naked Singularities ◽  
Asymptotic Flatness ◽  
Sitter Background ◽  
Strong Curvature

We investigate the occurrence of naked singularities in the gravitational collapse of an inhomogeneous dust cloud in an expanding de Sitter background — a piece of Tolman–Bondi–de Sitter space–time. It turns out that the collapse proceed in the same way as in the Minkowski background, i.e., the strong curvature naked singularities form and thus violate the cosmic censorship conjecture. Our result unambiguously support the fact that the asymptotic flatness of space–time is not a necessary ingredient for the development of naked singularities.

scholarly journals SPHERICALLY SYMMETRIC GRAVITATIONAL COLLAPSE OF A DUST CLOUD IN THIRD-ORDER LOVELOCK GRAVITY

2011 ◽  
Vol 20 (12) ◽  
pp. 2317-2335 ◽  
Author(s):  
KANG ZHOU ◽  
ZHAN-YING YANG ◽  
DE-CHENG ZOU ◽  
RUI-HONG YUE
Keyword(s):  
Gravitational Collapse ◽  
Dust Cloud ◽  
Cosmic Censorship ◽  
High Order ◽  
Spherically Symmetric ◽  
Lovelock Gravity ◽  
Third Order ◽  
Relativistic Case ◽  
Naked Singularities ◽  
Cosmic Censorship Hypothesis

We investigate the spherically symmetric gravitational collapse of an incoherent dust cloud by considering a LTB-type spacetime in third-order Lovelock Gravity without cosmological constant, and give three families of LTB-like solutions which separately corresponding to hyperbolic, parabolic and elliptic. Notice that the contribution of high-order curvature corrections have a profound influence on the nature of the singularity, and the global structure of spacetime changes drastically from the analogous general relativistic case. Interestingly, the presence of high order Lovelock terms leads to the formation of massive, naked and timelike singularities in the 7D spacetime, which is disallowed in general relativity. Moveover, we point out that the naked singularities in the 7D case may be gravitational weak therefore may not be a serious threat to the cosmic censorship hypothesis, while the naked singularities in the D ≥ 8 inhomogeneous collapse violate the cosmic censorship hypothesis seriously.

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.

The physics of black holes II

2018 ◽  
Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Energy Condition ◽  
Kerr Black Hole ◽  
Cosmic Censorship ◽  
Quantum Field ◽  
Schwarzschild Solution ◽  
Physics Of Black Holes ◽  
Penrose Process ◽  
Cosmic Censorship Hypothesis

This chapter gives a brief description of Hawking radiation, which involves a combination of general relativity and quantum field theory and leads to a thermodynamical interpretation of the laws governing the evolution of black holes. The study of the Penrose process near a Kerr black hole leads to the conclusion that its irreducible mass can only increase. A similar but more general conclusion was reached by Hawking, who showed that the sum of the areas of the horizons of black holes interacting with matter can only increase, with the condition that the cosmic censorship hypothesis is valid and that the matter obeys the so-called weak energy condition. The chapter concludes with the Israel theorem, which allows one to argue that if gravitation is described by general relativity, then not only do black holes exist, but all black holes are represented by the Kerr–Schwarzschild solution.

NATURE OF THE SINGULARITIES IN HIGHER-DIMENSIONAL HUSAIN SPACE–TIME

2006 ◽  
Vol 15 (09) ◽  
pp. 1359-1371 ◽  
Author(s):  
K. D. PATIL ◽  
S. S. ZADE
Keyword(s):  
Gravitational Collapse ◽  
Dimensional Space ◽  
Higher Dimensions ◽  
Cosmic Censorship ◽  
Space Time ◽  
Spherically Symmetric ◽  
Naked Singularities ◽  
Higher Dimensional ◽  
Dimensional Space Time ◽  
Cosmic Censorship Hypothesis

We generalize the earlier studies on the spherically symmetric gravitational collapse in four-dimensional space–time to higher dimensions. It is found that the central singularities may be naked in higher dimensions but depend sensitively on the choices of the parameters. These naked singularities are found to be gravitationally strong that violate the cosmic censorship hypothesis.

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