Do all QSOs have the same black hole mass?

Understand

QSOs from SDSS, 2QZ and 2SLAQ covering an order of magnitude in luminosity at fixed redshift exhibit similar amplitudes of clustering.

• In addition, QSO clustering evolution at z>0.5 is well fitted by a model that assumes a fixed host halo mass, implying that QSOs may occur in a relatively narrow range of halo and BH mass.
• We argue that the slow evolution of early-type galaxies out to z~1-2 may also provide support for a slow evolution of QSO host BH masses.
• The result would mean that if high-z QSOs radiate at Eddington rates then low-z SyI must radiate at ~100x less than Eddington.