Abstract
The most massive black holes lie in the most massive elliptical galaxies, and at low- z all radio-loud AGNs lie in giant ellipticals. This strongly suggests a link between radio-loudness and black hole mass. We argue that the increase in the radio-loud fraction with AGN luminosity in optically-selected quasar samples is consistent with this picture. We also use the ratio of black holes today to quasars at z∼2 to conclude that the most bolometrically-luminous AGN, either radio-loud or radio quiet, are constrained to have lifetimes ≲10 8 yr. If radio sources are associated with black holes of ≳10 9 M ⊙ at all redshifts, then the same lifetime constraint applies to all radio sources with luminosities above L 5GHz∼10 24 WHz −1 sr −1.
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