Global structure and stability of Kerr-Bertotti-Robinson spacetime
Abstract
The surface r=∞ of the Kerr-Bertotti-Robinson spacetime is not a genuine boundary. We construct its natural analytic extension and show that r=+∞ of one KBR region is smoothly connected to r=−∞ of a neighboring one. Repeated continuation produces an infinite chain of regions connected by wormhole-like bridges and exposes the neighboring ring singularity without an intervening horizon, which violates the weak cosmic censorship conjecture. We then study a test massless scalar field on a two-universe scattering segment to probe the stability of the spacetime. For axisymmetric perturbations, we analytically establish purely imaginary growing quasinormal modes for every ℓ and trace their origin to the chronology-violating region. In the (ℓ,m)=(2,2) sector, unstable branches occur for sufficiently large rotation and sufficiently small magnetic field. Their marginal real modes obey an exact horizon-flux balance, supporting a black-hole-bomb interpretation in which superradiant extraction is amplified by trapping within the double-barrier potential. The same cavity also supports families of weakly damped modes and may produce echo-like responses.
Related
- On the Extended Kerr-Newman-Bertotti-Robinson Spacetime: Two Black Holes and a Naked Singularity in Bertotti-Robinson Universe
- Local tests of Schwarzschild-Bertotti-Robinson spacetime
- External magnetic-field effects on dipolar-particle orbits and critical collisions in Kerr--Bertotti--Robinson spacetime
- Meissner effect in Kerr–Bertotti–Robinson spacetime
- From Bertotti–Robinson to vacuum: New exact solutions in general relativity via Harrison and Inversion symmetries
BibTeX
@misc{zhou2026global,
title = {{Global structure and stability of Kerr-Bertotti-Robinson spacetime}},
author = {Yu-Sen Zhou and Liang-Bi Wu and Ming-Fei Ji and Wen-Tao Fu and Li-Ming Cao and Rong-Gen Cai},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.07602},
eprint = {2609.07602},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.07602},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Global structure and stability of Kerr-Bertotti-Robinson spacetime
AU - Yu-Sen Zhou
AU - Liang-Bi Wu
AU - Ming-Fei Ji
AU - Wen-Tao Fu
AU - Li-Ming Cao
AU - Rong-Gen Cai
PY - 2026
DA - 2026/09/07
PB - arXiv
DO - 10.48550/arxiv.2609.07602
UR - https://arxiv.org/abs/2609.07602
AB - The surface r=∞ of the Kerr-Bertotti-Robinson spacetime is not a genuine boundary. We construct its natural analytic extension and show that r=+∞ of one KBR region is smoothly connected to r=−∞ of a neighboring one. Repeated continuation produces an infinite chain of regions connected by wormhole-like bridges and exposes the neighboring ring singularity without an intervening horizon, which violates the weak cosmic censorship conjecture. We then study a test massless scalar field on a two-universe scattering segment to probe the stability of the spacetime. For axisymmetric perturbations, we analytically establish purely imaginary growing quasinormal modes for every ℓ and trace their origin to the chronology-violating region. In the (ℓ,m)=(2,2) sector, unstable branches occur for sufficiently large rotation and sufficiently small magnetic field. Their marginal real modes obey an exact horizon-flux balance, supporting a black-hole-bomb interpretation in which superradiant extraction is amplified by trapping within the double-barrier potential. The same cavity also supports families of weakly damped modes and may produce echo-like responses.
ER -