Semiclassical gravity effects near horizon formation

Abstract

We study the magnitude of semiclassical gravity effects near the formation of a black-hole horizon in spherically-symmetric spacetimes. As a probe for these effects we use a quantised massless scalar field. Specifically, we calculate two quantities derived from it: the renormalised stress-energy tensor (a measure of how the field vacuum state affects the spacetime) and the effective temperature function (a generalisation of Hawking temperature related to the energy flux of the field vacuum). The subject of our study are spacetimes which contain a spherical distribution of matter and an empty exterior Schwarzschild region, separated by a surface which is moving in proximity to the Schwarzschild radius $r_{\mathrm{s}}=2M$, with $M$ the total mass. In particular, we analyse the consequences of three types of surface movement: an oscillation just above $r_{\mathrm{s}}$, a monotonous approach towards $r_{\mathrm{s}}$ in infinite time and a crossing of $r_{\mathrm{s}}$ at different velocities. For a collapsing matter distribution which follows the expected dynamical evolution in general relativity, we recover the standard picture of black-hole formation and its tenuous semiclassical effects. In more general dynamical regimes, allowing deviations from the standard classical evolution, we obtain a variety of different effects: from the emission of Hawking-like radiation without the formation of a horizon, to large values of the renormalised stress-energy tensor, related to the Boulware vacuum divergence in static spacetimes.

arXiv comment41 pages, 19 figures, v2: added one new figure and minor changes in text to match published version

References in corpus (29)

• Testing the nature of dark compact objects: a status report
• Isolated and dynamical horizons and their applications
• Stable gravastars - an alternative to black holes?
• Gravitational Energy in Spherical Symmetry
• The observational evidence for horizons: from echoes to precision gravitational-wave physics
• Tests for the existence of horizons through gravitational wave echoes
• Black hole fireworks: quantum-gravity effects outside the horizon spark black to white hole tunneling
• Twilight for the energy conditions?
• Regular coordinate systems for Schwarzschild and other spherical spacetimes
• A Primer on Energy Conditions
• Fate of gravitational collapse in semiclassical gravity
• Phenomenological aspects of black holes beyond general relativity
• Gravitational vacuum polarization II: Energy conditions in the Boulware vacuum
• The Internal Geometry of an Evaporating Black Hole
• Minimal conditions for the existence of a Hawking-like flux
• Physical observability of horizons
• The lifetime problem of evaporating black holes: mutiny or resignation
• Causal structure of acoustic spacetimes
• New theoretical approaches to black holes
• Quasi-particle creation by analogue black holes
• Nonthermal nature of incipient extremal black holes
• Mutiny at the white-hole district
• Radiation from collapsing shells, semiclassical backreaction and black hole formation
• Spherically symmetric trapping horizons, the Misner-Sharp mass and black hole evaporation
• Black hole kinematics: the "in"-vacuum energy density and flux for different observers
• Two formalisms, one renormalized stress-energy tensor
• A tensorial description of particle perception in black-hole physics
• Particle creation in gravitational collapse to a horizonless compact object
• Model for Quantum Effects in Stellar Collapse

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• Robustness of particle creation in the formation of a compact object
• Quantum Critical Collapse Abhors a Naked Singularity
• Wave equations in conformally separable, accreting, rotating black holes
• Asymptotic horizon formation, spacetime stretching and causality
• Shadow formation in gravitational collapse: Redshift and blueshift by spacetime dynamics
• Observables in quantum field theory on a collapsing black hole background