Towards the black hole uniqueness: transverse deformations of the extremal Reissner-Nordström-(A)dS horizon

Abstract: We study all transverse deformations of the extremal Reissner-Nordstr\"{o}m-(A)dS horizon in the Einstein-Maxwell theory. No symmetry assumptions are needed. It is shown that for the generic values of the charge, the only allowed deformation is spherically symmetric. However, it is shown that for fine-tuned values of a charge, the space of deformations is larger, yet still finite-dimensional.