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Recently, the possibility was pointed out by one of the present authors and his collaborators that an effective naked singularity referred to as "a visible border of spacetime" is generated by high-energy particle collision in the context…

General Relativity and Quantum Cosmology · Physics 2011-05-12 Umpei Miyamoto , Hiroya Nemoto , Masahiro Shimano

We show that the naked singularities arising in dust collapse from smooth initial data (which include those discovered by Eardley and Smarr, Christodoulou, and Newman) are removed when we make transition to higher dimensional spacetimes.…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Rituparno Goswami , Pankaj S Joshi

In the case of unhindered gravitational collapse of matter cloud governed by the Lemaitre-Tolman-Bondi (LTB) spacetime, the end-state singularity is either locally visible, globally visible or completely hidden. We have a past-null…

General Relativity and Quantum Cosmology · Physics 2024-02-23 Ashok B. Joshi , Karim Mosani , Pankaj S. Joshi

We present here an overview of our basic understanding and recent developments on spacetime singularities in the Einstein theory of gravity. Several issues related to physical significance and implications of singularities are discussed.…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Pankaj S. Joshi

The critical collapse of a scalar field is a threshold solution of black hole formation, in which a naked singularity arises. We study here the curvature strength of this singularity using a numerical ansatz. The behavior of the Jacobi…

General Relativity and Quantum Cosmology · Physics 2020-11-16 Jun-Qi Guo , Lin Zhang , Yuewen Chen , Pankaj S. Joshi , Hongsheng Zhang

We study the occurrence of naked singularities in the spherically symmetric collapse of a charged null fluid in an expanding deSitter background - a piece of charged Vaidya-deSitter spacetime. The necessary conditions for the formation of a…

General Relativity and Quantum Cosmology · Physics 2009-10-31 A. Beesham , S. G. Ghosh

We investigate here the genericity and stability aspects for naked singularities and black holes that arise as the final states for a complete gravitational collapse of a spherical massive matter cloud. The form of the matter considered is…

General Relativity and Quantum Cosmology · Physics 2012-11-15 Pankaj S. Joshi , Daniele Malafarina , Ravindra V. Saraykar

We show that the behaviour of outgoing radial null geodesic congruence on the apparent horizon is related to the property of nakedness in spherical dust collapse justifying the difference between the Penrose diagrams in the naked and…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Sukratu Barve

The final state--black hole or naked singularity--of the gravitational collapse of a marginally bound matter configuration in the presence of tangential stresses is classified, in full generality, in terms of the initial data and equation…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Sergio M. C. V. Goncalves , Sanjay Jhingan , Giulio Magli

In this paper we analyze the redshift as observed by an external observer receiving photons which terminate in the past at the naked singularity formed in a Tolman-Bondi dust collapse. Within the context of models considered here it is…

General Relativity and Quantum Cosmology · Physics 2009-10-31 I. H. Dwivedi

In this paper, we consider the gravitational collapse of generalized Vaidya space-time when the matter satisfies the equation of the state either $P=0$ or $P=-\alpha \rho$, where $0 < \alpha < 1$. We show that in the case when type I of…

General Relativity and Quantum Cosmology · Physics 2022-10-31 Vitalii Vertogradov

We consider spherically symmetric spacetimes with matter whose timelike flow is assumed to be shear-free. A number of results on the formation and visibility of spacetime singularities is proven, with the main one being that shear-free…

General Relativity and Quantum Cosmology · Physics 2010-05-12 Sergio M. C. V. Goncalves

The collapse of thin dust shells in 2+1 dimensional gravity with and without a cosmological constant in analyzed. A critical value of the shell's mass as a function of its radius and position is derived. For $\Lambda < 0$, a naked…

General Relativity and Quantum Cosmology · Physics 2009-12-30 Yoav Peleg , Alan Steif

Various types of inhomogeneous collapse models in general relativity (GR) lead to the formation of spacetime singularities either visible or hidden by a spacetime horizon. Our aim in the present work is to search for nonsingular models in…

General Relativity and Quantum Cosmology · Physics 2025-07-04 Akbar Jahan , Halime Miraghaei , Shayesteh Ghaffari , Amir Hadi Ziaie

We consider general relativistic homogeneous gravitational collapses for dust and radiation. We show that replacing the density profile with an effective density justified by some quantum gravity framework leads to the avoidance of the…

General Relativity and Quantum Cosmology · Physics 2013-08-07 Cosimo Bambi , Daniele Malafarina , Leonardo Modesto

A new mechanism for causing naked singularities is found in an effective superstring theory. We investigate the gravitational collapse in a spherically symmetric Einstein-Maxwell-dilaton system in the presence of a pure cosmological…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Kengo Maeda , Takashi Torii , Makoto Narita

We study stability of occurrence of black holes and naked singularities that arise as a final state for a complete gravitational collapse of type I matter field in a spherically symmetric $N$ dimensional spacetime with equation of state $p…

General Relativity and Quantum Cosmology · Physics 2014-11-26 Sanjay Sarwe , R. V. Saraykar

Assuming the weak energy condition, we study the nature of the non-central shell-focussing singularity which can form in the gravitational collapse of a spherical compact object in classical general relativity. We show that if the radial…

General Relativity and Quantum Cosmology · Physics 2009-10-28 F. I. Cooperstock , S. Jhingan , P. S. Joshi , T. P. Singh

We investigate here the causal structure of spacetime in the vicinity of a spacetime singularity. The particle and energy emission from such ultra-dense regions forming in gravitational collapse of a massive matter cloud is governed by the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Pankaj S. Joshi

By considering families of radial null geodesics, we study the subsets of initial data that lead to naked singularities and black holes in inhomogeneous spherical dust collapse. We introduce the notion of central homogeneity for spherical…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Filipe C. Mena , Reza Tavakol , Pankaj S. Joshi
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