C IV EMISSION AND THE ULTRAVIOLET THROUGH X-RAY SPECTRAL ENERGY DISTRIBUTION OF RADIO-QUIET QUASARS

In the rest-frame ultraviolet (UV), two of the parameters that best characterize the range of emission-line properties in quasar broad emission-line regions are the equivalent width and the blueshift of the C IV {lambda}1549 line relative to the quasar rest frame. We explore the connection between these emission-line properties and the UV through X-ray spectral energy distribution (SED) for radio-quiet (RQ) quasars. Our sample consists of a heterogeneous compilation of 406 quasars from the Sloan Digital Sky Survey (at z > 1.54) and Palomar-Green survey (at z < 0.4) that have well-measured C IV emission-line and X-ray properties (including 164 objects with measured {Gamma}). We find that RQ quasars with both strong C IV emission and small C IV blueshifts can be classified as 'hard-spectrum' sources that are (relatively) strong in the X-ray as compared to the UV. On the other hand, RQ quasars with both weak C IV emission and large C IV blueshifts are instead 'soft-spectrum' sources that are (relatively) weak in the X-ray as compared to the UV. This work helps to further bridge optical/soft X-ray 'eigenvector 1' relationships to the UV and hard X-ray. Based on these findings, we argue that future work should consider systematicmore » errors in bolometric corrections (and thus accretion rates) that are derived from a single mean SED. Detailed analysis of the C IV emission line may allow for SED-dependent corrections to these quantities.« less