“…This turns out to be useful also for the analysis of qualitative spectral properties ofĤ. It is worth mentioning that the aforementioned problem associated with variable separation in Chandrasekhar ansatz and the occurrence of two Hilbert spaces in the analysis of the Dirac equation have been already pointed out in [9] for the case of the Dirac equation on a black hole background of the Kerr-Newman family, which has been considered in several studies [10,11,12,13,14,15] (see also [16]); the above part of our analysis can be of interest also for that case. Moreover, our analysis points out some relevant differences to be related to the AdS background considered herein, and also introduces some interesting analysis to be associated with a magnetically charged black hole: we find the Dirac charge quantization as a condition ensuring essential selfadjointness for the Hamiltonian operatorĤ on C ∞ 0 ((r + , ∞) × S 2 ) 4 .…”