Naked singularities and quantum gravity

Abstract

There are known models of spherical gravitational collapse in which the collapse ends in a naked shell-focusing singularity for some initial data. If a massless scalar field is quantized on the classical background provided by such a star, it is found that the outgoing quantum flux of the scalar field diverges in the approach to the Cauchy horizon. We argue that the semiclassical approximation (i.e. quantum field theory on a classical curved background) used in these analyses ceases to be valid about one Planck time before the epoch of naked singularity formation, because by then the curvature in the central region of the star reaches Planck scale. It is shown that during the epoch in which the semiclassical approximation is valid, the total emitted energy is about one Planck unit, and is not divergent. We also argue that back reaction in this model does not become important so long as gravity can be treated classically. It follows that the further evolution of the star will be determined by quantum gravitational effects, and without invoking quantum gravity it is not possible to say whether the star radiates away on a short time scale or settles down into a black hole state.

16 pages, paper rewritten into sections, conclusions unchanged, 4 references added, to appear in Phys. Rev. D (Rapid Communication)

References in corpus (6)

• Toward a Midisuperspace Quantization of LeMaitre-Tolman-Bondi Collapse Models
• Naked Singularity Explosion
• Power, energy, and spectrum of a naked singularity explosion
• Gamma-ray bursts as the birth-cries of black holes
• Divergence of the Quantum Stress Tensor on the Cauchy Horizon in 2-d Dust Collapse
• Quantum Radiation from Black Holes and Naked Singularities in Spherical Dust Collapse

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• How Does Naked Singularity Look?
• Appearance of the central singularity in spherical collapse
• Physical aspects of naked singularity explosion - How does a naked singularity explode? --
• Classical and Quantum Gravitational Collapse in d-dim AdS Spacetime I. Classical Solutions
• Naked singularity in 4D Einstein-Gauss-Bonnet novel gravity: Echoes and (in)-stability
• Toward a Quantization of Null Dust Collapse
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• Singularity at the demise of a black hole
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• Exact Analytical Taub-NUT like Solution in f(T) Gravity
• Reissner Nordström Background Metric in Dynamical Co-ordinates: Exceptional Behaviour of Hadamard States