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We calculate the quantum stress tensor for a massless scalar field in the 2-d self-similar spherical dust collapse model which admits a naked singularity. We find that the outgoing radiation flux diverges on the Cauchy horizon. This may…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Sukratu Barve , T. P. Singh , Cenalo Vaz , Louis Witten

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

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

The hypothesis of cosmic censorship (CCH) plays a crucial role in classical general relativity, namely to ensure that naked singularities would never emerge, since it predicts that whenever a singularity is formed an event horizon would…

General Relativity and Quantum Cosmology · Physics 2017-04-26 Nikolaos Pappas

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

We investigate the occurrence and nature of naked singularities in the Szekeres space-times. These space-times represent irrotational dust. They do not have any Killing vectors and they are generalisations of the Tolman-Bondi-Lemaitre…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Pankaj S. Joshi , Andrzej Krolak

Penrose's weak cosmic censorship conjecture asserts that spacetime singularities produced by gravitational collapse are generically hidden behind event horizons, thus preventing them from causally influencing distant observers and…

General Relativity and Quantum Cosmology · Physics 2026-03-16 Giovanni Caridi , Fabrizio Corelli , Paolo Pani

We investigate the fate of the classical singularity in a collapsing dust cloud. For this purpose, we quantize the marginally bound Lemaitre-Tolman-Bondi model for spherically-symmetric dust collapse by considering each dust shell in the…

General Relativity and Quantum Cosmology · Physics 2019-06-19 Claus Kiefer , Tim Schmitz

We consider the end state of collapsing null radiation with a string fluid. It is shown that, if diffusive transport is assumed for the string, that a naked singularity can form (at least locally). The model has the advantage of not being…

General Relativity and Quantum Cosmology · Physics 2009-11-10 K S Govinder , M Govender

The collapse of marginally bound, inhomogeneous, pressureless (dust) matter, in spherical symmetry, is considered. The starting point is not, in this case, the integration of the Einstein equations from some suitable initial conditions.…

General Relativity and Quantum Cosmology · Physics 2018-04-27 Ramon Lapiedra , Juan Antonio Morales-Lladosa

For any asymptotically flat spacetime with a suitable causal structure obeying (a weak form of) Penrose's cosmic censorship conjecture and satisfying conditions guaranteeing focusing of complete null geodesics, we prove that active…

General Relativity and Quantum Cosmology · Physics 2010-04-06 G. J. Galloway , E. Woolgar

We present a class of curved-spacetime vacuum solutions which develope closed timelike curves at some particular moment. We then use these vacuum solutions to construct a time-machine model. The causality violation occurs inside an empty…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Amos Ori

The visibility of the shell-focusing singularity in Szekeres space-time - which represents quasi-spherical dust collapse - has been studied on numerous occasions in the context of the cosmic censorship conjecture. The various results…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Brien C. Nolan , Ujjal Debnath

We consider here the gravitational collapse of a spherically symmetric inhomogeneous dust cloud described by the Tolman-Bondi models. By studying a general class of these models, we find that the end state of the collapse is either a black…

General Relativity and Quantum Cosmology · Physics 2009-10-22 P. S. Joshi , T. P. Singh

We show that, in principle, a slowly evolving gravitationally collapsing perfect fluid cloud can asymptotically settle to a static spherically symmetric equilibrium configuration with a naked singularity at the center. We consider one such…

General Relativity and Quantum Cosmology · Physics 2015-06-15 Pankaj S. Joshi , Daniele Malafarina , Ramesh Narayan

According to conventional modelling by general relativity the collapse of radially symmetric gravitating objects may end in a singular state. But by inclusion of potential energy into the energy tensor, which is required to guarantee global…

General Physics · Physics 2013-03-27 Ernst Fischer

It is shown that gauged nonlinear sigma models can be always deformed by terms proportional to the field strength of the gauge fields (nonminimal gauging). These deformations can be interpreted as perturbations, by marginal operators, of…

High Energy Physics - Theory · Physics 2009-10-22 Noureddine Mohammedi

We study here the spherical gravitational collapse assuming initial data to be necessarily smooth, as motivated by the requirements based on physical reasonableness. A tangential pressure model is constructed and analyzed in order to…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Ashutosh Mahajan , Rituparno Goswami , 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

It is now known that when a massive star collapses under the force of its own gravity, the final fate of such a continual gravitational collapse will be either a black hole or a naked singularity under a wide variety of physically…

General Relativity and Quantum Cosmology · Physics 2012-04-20 Pankaj S. Joshi , Daniele Malafarina