The hard band X-ray luminosities (upper panel) and SMBH e-folding times in units of the Hubble time (lower panel) for various black hole masses as shown in the legend. For the low mass SMBHs at higher redshifts, where they are too faint to be constrained by the observational data, we have shown the extrapolations of the model curves with dotted lines and have omitted the corresponding 1σ uncertainty bands.