The Cosmogony of Super-Massive Black Holes

• The luminosities of the quasars with the largest redshifts indicate that central BH masses of > 10 M⊙ were already present when the Universe was less than 10 years old (Barth et al. 2003). These masses are lower limits as they are based on the assumption that the BHs accrete at their Eddington limit. There is no indication that the (majority of the) sample of highest-redshift-quasar luminosities is afflicted by amplification by gravitational lensing (White et al. 2005). • Surveys in the X-ray regime (Hasinger et al. 2005) and in the optical/UV regime (Wolf et al. 2003) show a strong luminosity dependence of the redshift at which the active galactic nuclei (AGN) space density peaks: The lower the AGN luminosity, i.e., the smaller the BH mass, the later in the evolution of the Universe the co-moving space density of these AGN peaks. In other words, it takes BHs of a lower final mass longer to reach that mass than BHs of a larger final mass. This is also supported by a comparison of the local and the derived accretion mass function of SMBHs (Shankar et al. 2004).