Charged Black Holes: Wave Equations for Gravitational and Electromagnetic Perturbations

A pair of wave equations for the electromagnetic and gravitational perturbations of a charged Kerr black hole are derived. The perturbed Einstein-Maxwell equations in a new gauge are employed in the derivation. The wave equations refer to the perturbed Maxwell spinor (phi)0 and to the shear (sigma) of a principal null direction of the Weyl curvature. The whole construction rests on the tripod of three distinct derivatives of the first curvature k of a principal null direction.