Particle acceleration and curvature TeV emission by rotating, supermassiveblack holes

It is shown that particles accelerating near the event horizon of a spinnin g supermassive black hole that is threaded by externally supported magnetic field lines suffer severe curvature losses that limit the maximum energy t hey can attain to values well below that imposed by the maximum voltage dro p induced by the black hole dynamo. It is further shown that the dominant f raction of the rotational energy extracted from the black hole is radiated in the TeV band. The implications for vacuum breakdown and the observationa l consequences are discussed.