Black hole evaporation and semiclassicality at large D

Abstract

Black holes of sufficiently large initial radius are expected to be well described by a semiclassical analysis at least until half of their initial mass has evaporated away. For a small number of spacetime dimensions, this holds as long as the black hole is parametrically larger than the Planck length. In that case, curvatures are small and backreaction onto geometry is expected to be well described by a time-dependent classical metric. We point out that at large $D$, small curvature is insufficient to guarantee a valid semiclassical description of black holes. Instead, the strongest bounds come from demanding that the rate of change of the geometry is small and that black holes scramble information faster than they evaporate. This is a consequence of the enormous power of Hawking radiation in $D$-dimensions due to the large available phase space and the resulting minuscule evaporation times. Asymptotically, only black holes with entropies $S\ge D^{D+3}\log D$ are semiclassical. We comment on implications for realistic quantum gravity models in $D\le 26$ as well as relations to bounds on theories with a large number of gravitationally interacting light species.

6 pages

References in corpus (5)

• Black holes as mirrors: quantum information in random subsystems
• Black Hole Bound on the Number of Species and Quantum Gravity at LHC
• Black hole collisions, instabilities, and cosmic censorship violation at large D
• Hyperentropic systems and the generalized second law of thermodynamics
• The holographic entropy bound in higher-dimensional spacetimes: As strong as ever

Cited by in corpus (8)

• The Large D Limit of Einstein's Equations
• Ultralight Fermionic Dark Matter
• Hawking evaporation of Einstein-Gauss-Bonnet AdS black holes in $D⩾4$ dimensions
• Unitary Constraints on Semiclassical Schwarzschild Black Holes in the Presence of Island
• Holographic duals of evaporating black holes
• Island of Reissner-Nordstr$\ddot{\mathbf{o}}$m anti-de Sitter black holes in the large $d$ limit
• Isentropic processes for axisymmetric Black Holes
• Scrambling and the black hole atmosphere