2003ApJ...597L..17S

We consider the properties of radio-loud (RL) active galactic nuclei in the context of the eigenvector 1 (E1) parameter space. RL sources show a restricted E1 parameter space occupation relative to the radio-quiet (RQ) majority. The Fanaroff-Riley II ``parent population'' of relatively unboosted RL sources (median radio/optical flux ratio ∼490) shows the most restricted occupation. RL sources have different broad-line properties (and inferred black hole masses and Eddington ratios). FWHM Hβ for the broad-line component in RL sources are at least twice as large as in the RQ majority. The average broad Fe II λ4570 emission-line strength is also about half that for RQ sources. Our sample suggests that the RL cutoff occurs near R_K~70 or logP_6cm∼32.0 ergs/s/Hz. Sources below this cutoff are RQ, although we cannot rule out the existence of a distinct intermediate population. We show that the Doppler-boosted core-dominated RL sources (median flux ratio ∼1000) lie toward smaller FWHM(Hβ_BC) and stronger Fe II_optin E1, as expected if the lines arise in an accretion disk. Our subsample of superluminal sources, with orientation inferred from the synchrotron self-Compton model, reinforce this general E1 trend and allow us to estimate the role of source orientation in driving E1 domain occupation.