Black hole to grey hole metamorphosis in the deep quantum regime

Abstract In order to search for new solutions for collapsed objects in quantum gravity, we consider in this paper a Kantowski–Sachs metric labelled by parameters that have no classical significance. In addition, we include a Klein–Gordon field to represent in a simple manner the inevitable zero-point vacuum fluctuations that permeate the spacetime. With this framework, we quantize the system and obtain the Wheeler–DeWitt equation in order to focus upon the deep quantum regime of the interior and to analyze any kind of transition that the black hole may undergo. The Wheeler–DeWitt equation reveals the existence of new solutions of different nature, designated herein as “quantum grey holes,” in addition to the existence of quantum black holes, with all solutions satisfying the DeWitt boundary condition. The existence of new solutions gives rise to the novel possibility of a quantum black hole making a transition to a quantum grey hole. We find that there exists non-zero probability of quantum black-to-grey hole transition. These transition probabilities exhibit resonances for a continuous range of eigenvalues of the system.