Uniqueness of extremal Kerr and Kerr-Newman black holes
Uniqueness of extremal Kerr and Kerr-Newman black holes
We prove that the only four-dimensional, stationary, rotating, asymptotically flat (analytic) vacuum black hole with a single degenerate horizon is given by the extremal Kerr solution. We also prove a similar uniqueness theorem for the extremal Kerr-Newman solution. This closes a long-standing gap in the black hole uniqueness theorems.