The symbiotic system in quasars: black hole, accretion disk and jet

The UV continuum spectrum of quasars and AGN is assumed to originate from an accreting disk surrounding a massive rotating black hole. We discuss the structure and emission spectra of a disk which drives a powerful jet. Due to the large efficiency of extracting energy from the accreting matter in the inner part of the disk close to the massive object, all the energetic conditions for the formation of jets are fulfilled. The total energy going up into the jet depends strongly on the Kerr black hole parameters, on the disk features and on the mass flow and thickness of the jet. The shape of UV spectra of the AGN can be explained by a sub-Eddington accretion disk which drives a jet in the innermost parts.