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We present an analysis of the AGN broad-line regions of 6 powerful radiogalaxies at z>~2 (HzRGs) with rest-frame optical imaging spectroscopy obtainedat the VLT. All galaxies have luminous (L(H-alpha)=few x 10^44 erg s^-1),spatially unresolved H-alpha line emission with FWHM>= 10,000 km s^-1 at theposition of the nucleus, suggesting their AGN are powered by supermassive blackholes with masses of few x 10^9 M_sun and accretion luminosities of a fewpercent of the Eddington luminosity. In two galaxies we also detect the BLRs inH-beta, suggesting relatively low extinction of A_V~1 mag, which agrees withconstraints from X-ray observations. By relating black hole and bulge mass, wefind a possible offset towards higher black-hole masses of at most ~0.6 dexrelative to nearby galaxies at a given host mass, although each individualgalaxy is within the scatter of the local relationship. If not entirely fromsystematic effects, this would then suggest that the masses of the hostgalaxies have increased by at most a factor ~4 since z~2 relative to theblack-hole masses, perhaps through accretion of satellite galaxies or becauseof a time lag between star formation in the host galaxy and AGN fueling. Wealso compare the radiative and mechanical energy output (from jets) of ourtargets with predictions of recent models of "synthesis" or "grand unified" AGNfeedback, which postulate that AGN with similar radiative and mechanical energyoutput rates to those found in our HzRGs may be nearing the end of their periodof active growth. We discuss evidence that they may reach this stage at thesame time as their host galaxies.

The black holes of radio galaxies during the "Quasar Era": Masses, accretion rates, and evolutionary stage