A possible correlation between the luminosities and lifetimes of active galactic nuclei

We use the clustering of galaxies around distant AGNs to show with similar to 90% confidence that fainter AGNs are longer lived. Our argument is simple: since the measured galaxy- AGN cross- correlation length r(0) similar to 5 h (-1) Mpc does not vary significantly over a 10 mag range in AGN optical luminosity, faint and bright AGNs must reside in dark matter halos with similar masses. The halos that host bright and faint AGNs must therefore have similar abundances, and bright AGNs are rare partly because their lifetimes are short.