Radio - Optical Correlations in High-z Radio Galaxies and Quasars
  The narrow emission line luminosities of radio-loud AGN are well-correlated with their low-frequency radio luminosities. This correlation is linear and extends over at least four orders of magnitude. The correlation is discussed in terms of a linear relationship between the power in the radio-emitting jets and the photoionizing (i.e. accretion) luminosity. Support for this theory comes from a direct correlation between the optical continuum and radio luminosities of steep-spectrum quasars. We discuss the dependence of the observed luminosities of AGN on their black hole masses and how close to the Eddington limit they are accreting. 
Chris J. Willott