Light rings of stationary spacetimes
arXiv:2107.07370 · doi:10.1103/PhysRevD.104.044019
Abstract
We present a novel theorem regarding light rings in a stationary spacetime with an ergoregion. We prove that any stationary, axisymmetric, and asymptotically flat spacetime in 1 + 3 dimensions with an ergoregion must have at least one light ring outside the ergoregion. A possible extension of the proof for asymptotically de-Sitter and anti-de-Sitter spherically symmetric black holes is also discussed.
5 pages, no figure
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