Refining the Soltan argument: the parallel growth of black holes and galaxies
A. Merloni, G. Rudnick, T. Di Matteo
We compare all the available observational data on the redshift evolution of the total stellar mass and star formation rate density in the Universe with the mass and accretion rate density evolution of supermassive black hole. We find that on average black hole mass must have been higher at higher redshift for given spheroid stellar mass. Using a refined version of the classical Soltan argument, we discuss how constraints on radiative efficiency depend on the accretion mode.