Particle acceleration close to the supermassive black hole: the case of M87

HESS observations have shown M87 to be a rapidly (time scales of days) variable TeV emitting source. Due to its very low bolometric luminosity, the nucleus of M87 may already be transparent to TeV gamma-rays. We analyse the centrifugal acceleration of charged particles at the base of a rotating jet magnetospheres. It is shown that electrons may be a accelerated to very high Lorentz factors in the vicinity of the light cylinder, allowing inverse Compton upscattering of accretion disk photons to the very high energy domain. The results are compared to the observed spectrum and time variability