On Hawking’s Local Rigidity Theorems for Charged Black Holes

We show the existence of a Hawking vector field in a full neighborhood of a local, regular, bifurcate, non-expanding horizon embedded in a smooth Einstein-Maxwell space-time without assuming the underlying space-time is analytic. It extends one result of Friedrich, Rácz and Wald, see [3], which was limited to the interior of the black hole region. Moreover, we also show, in the presence of an additional Killing vector field T which tangent to the horizon and not vanishing on the bifurcate sphere, then spacetime must be locally axially symmetric without the analyticity assumption. This axial symmetry plays a fundamental role in the classification theory of stationary black holes.