Figure 4: Figure 5 from Merloni and Heinz [63], showing the redshift evolution of their estimated BHMF. The dashed line is the local BHMF and the shaded regions reflect the uncertainty in the BHMF that is due to uncertainties in the AGN luminosity function. The high mass end of their estimated BHMF is built up faster than the low-mass end, a phenomenon that has been called “downsizing”.