A New Orientation Indicator for Radio-Quiet Quasars

The velocities of the [O iii ] λ5007 and optical Fe ii emission lines, measured relative to the systemic redshifts of 2265 QSOs by Hu et al., show the signature of a disklike BLR structure with polar outflows. Objects with large [O iii ] outflows show no Fe ii offset velocity and are seen pole-on. Objects with large Fe ii inflow show no [O iii ] offset velocity and are seen edge-on. This interpretation is supported by the morphology of the radio-loud objects within the sample and by previous determinations of the geometry of the broad- and narrow-line regions. Analysis of the objects with neither Fe ii or [O iii ] velocity offsets, however, shows that the two groups also differ in Eddington ratio (ER), and, within this subset, corresponding groups with high and low ER but with the opposite orientation can be identified. Using these four subsets of the sample, the effects of orientation and ER can be separated, and, in some cases, quantified. The changes in apparent continuum luminosity and broad Hβ width and strength suggest a model in which both continuum and Hβ are emitted from the surface of the disk, which is less flattened in high ER objects. The effects of orientation on the derived properties, black hole mass and ER, are significant, though not large. The [O iii ] outflow appears to influence the width of that line, as well as its centroid.