Paper detail

The behavior of quasar C IV emission-line properties with orientation

With a quasar sample designed for studying orientation effects, we investigate the orientation dependence of characteristics of the C IV 1549 broad emission line in approximately 50 Type 1 quasars with z=0.1-1.4. Orientation is measured for the sample via radio core dominance. In our analysis we include measurements of the continuum luminosity and the optical-to-X-ray spectral slope, spectral properties commonly included in the suite known as "Eigenvector 1", and the full-width at half maximum, full-width at one-quarter-maximum, shape, blueshift, and equivalent width of the C IV broad emission line. We also investigate a new prescription that we recently developed for predicting the velocity line width of the H-beta broad emission line based on the velocity line width of the C IV line and the ratio of continuum subtracted peak fluxes of Si IV + O IV] at 1400 A to C IV. In addition to a correlation analysis of the ultraviolet spectral properties and radio core dominance, we provide composite spectra of edge-on and face-on sources for this sample. In particular, we highlight the orientation dependence of the velocity line width predicted for H-beta. We find that this predicted line width depends on orientation in a manner similar to the true velocity line width of H-beta, where no such dependence is observed for C IV. This is an indication that orientation information concerning the line emitting regions can be extracted from ultraviolet spectra. [abridged]