Several independent lines of evidence now point to a correlation between black hole mass , M _ { bh } , and radio-luminosity .
In this paper we discuss the correlation for quasars from the FIRST Bright Quasar Survey ( FBQS ) , using black hole mass estimates from H \beta linewidths .
The FBQS objects fill in the gap between the radio-loud and radio-quiet quasars in the radio-luminosity – optical-luminosity plane , and we find that they fill the corresponding gap in the M _ { bh } – radio luminosity correlation .
There is thus a continuous variation of radio luminosity with M _ { bh } , and no evidence for a “ switch ” at some set of critical parameter values which turns on powerful radio jets .
By combining the FBQS data with that for quasars from the Palomar-Green survey we find evidence for a dependence of radio-luminosity on accretion rate relative to the Eddington limit , L / L _ { Edd } , as well as on M _ { bh } , consistent with the well-known radio-optical correlation for radio-loud quasars .
We therefore suggest a new scheme to “ unify ” radio-loud and radio-quiet objects in which radio luminosity scales \propto M _ { bh } ^ { 1.9 \pm 0.2 } ( L / L _ { Edd } ) ^ { 1.0 } for L / L _ { Edd } \sim 0.1 , with an apparently weaker accretion rate dependence at low L / L _ { Edd } .
The scatter about this relation is \pm 1.1 dex , and may well hide significant contributions from other physical effects , such as black hole spin and radio source environment .