Null hypersurface caustics for high-dimensional superentropic black holes

A black hole is superentropic if it violates the reverse isoperimetric inequality. Recently, some studies have indicated that some four-dimensional superentropic black holes have the null hypersurface caustics (NHC) outside their event horizons. In this paper, we extend to explore whether or not the NHC exists in the cases of high-dimensional superentropic black holes. We consider the singly rotating Kerr-anti-de Sitter superentropic black holes in arbitrary dimensions and the singly rotating charged superentropic black hole in five-dimensional minimal gauged supergravity and find that the NHC exists outside the event horizons for these superentropic black holes. Furthermore, the spacetime dimensions and other parameters of the black hole, such as the electric charge, have an important impact on the NHC inside the horizon. Our results indicate that, when the superentropic black hole has the Cauchy horizon, the NHC will also exist inside the Cauchy horizon.

Automated summary

Recent studies show that high-dimensional superentropic black holes have null hypersurface caustics. The dimensions and parameters of the black hole greatly impact the caustics inside the horizon.