Superradiance in the BTZ black hole with Robin boundary conditions
arXiv:1710.08039 · doi:10.1016/j.physletb.2018.01.018
Abstract
We show the existence of superradiant modes of massive scalar fields propagating in BTZ black holes when certain Robin boundary conditions, which never include the commonly considered Dirichlet boundary conditions, are imposed at spatial infinity. These superradiant modes are defined as those solutions whose energy flux across the horizon is towards the exterior region. Differently from rotating, asymptotically flat black holes, we obtain that not all modes which grow up exponentially in time are superradiant; for some of these, the growth is sourced by a bulk instability of AdS3, triggered by the scalar field with Robin boundary conditions, rather than by energy extraction from the BTZ black hole. Thus, this setup provides an example wherein Bosonic modes with low frequency are pumping energy into, rather than extracting energy from, a rotating black hole.
10 pages, 5 figures
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Cited by in corpus (5)
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- Superradiant instability and charged scalar quasinormal modes for -dimensional Coulomb-like AdS black holes from nonlinear electrodynamics
- Quantum-corrected black holes and naked singularities in (2+1)-dimensions
- Robin boundary conditions in acoustic BTZ black holes
- Boundary conditions for isolated asymptotically anti-de Sitter spacetimes