M. Heusler, THE UNIQUENESS THEOREM FOR ROTATING BLACK-HOLE SOLUTIONS OF SELF-GRAVITATING HARMONIC-MAPPINGS, Classical and quantum gravity, 12(8), 1995, pp. 2021-2035
We consider rotating black hole configurations of self-gravitating map
s from spacetime into arbitrary Riemannian manifolds. We first establi
sh the integrability conditions for the Killing fields generating the
stationary and the axisymmetric isometry (circularity theorem). Restri
cting ourselves to mappings with harmonic action, we subsequently prov
e that the only stationary and axisymmetric, asymptotically flat black
hole solution with a regular event horizon is the Kerr metric. Togeth
er with the uniqueness result for non-rotating configurations and the
strong rigidity theorem, this establishes the uniqueness of the Kerr f
amily amongst all stationary black hole solutions of self-gravitating
harmonic mappings.