Signatures of black hole spin in galaxy evolution

We explore the connection between black hole spin and AGN power by addressing the consequences underlying the assumption in the recent literature that the gap region between accretion disks and black holes is fundamental in producing strong, spin-dependent, horizon-threading magnetic fields. Under the additional assumption that jets and outflows in AGN are produced by the BlandfordZnajek and Blandford-Payne mechanisms, we show that maximum jet/outflow power is achieved for accretion onto black holes having highly retrograde spin parameter, an energetically excited yet unstable gravitomagnetic configuration. Subject headings: galaxy: evolution — black hole physics