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.
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"