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Non-spherical horizon topology in 4D beyond GR

Investigate whether black rings or other black objects with non-spherical horizon topology can exist in four spacetime dimensions within theories beyond General Relativity, thereby extending the higher-dimensional abundance of horizon topologies to 4D.

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Background

In higher dimensions, black objects with non-spherical horizons (e.g., black rings, Saturns) are plentiful due to the flexibility of long horizons. In 4D GR, topological censorship forbids such objects, but beyond-GR theories may allow them.

This question probes whether modifying the gravitational sector could accommodate richer horizon topologies in 4D, paralleling the D>4 landscape.

References

Open questions: Would it be possible to obtain black rings or other black objects with non-spherical horizon topology in four dimensions in some theory beyond GR?

Black Holes Inside and Out 2024: visions for the future of black hole physics (2410.14414 - Afshordi et al., 18 Oct 2024) in Roberto Emparan, Section "Black holes in higher dimensions"