What does Civ{\lambda}1549 tell us about the physical driver of the Eigenvector Quasar Sequence?

TL;DR

This study investigates the physical drivers behind quasar emission line properties, revealing correlations between Civ1549 blueshift, Eddington ratio, and luminosity, and distinguishing outflow signatures across different quasar populations and luminosities.

Contribution

It provides new high S/N Civ1549 spectra for high-luminosity quasars and analyzes their relation to quasar accretion properties within the 4DE1 framework.

Findings

Civ1549 blueshift correlates with Eddington ratio.

Outflow signatures are present in Population A at low luminosity.

Outflows begin to appear in Population B at high luminosity.

Abstract

Broad emission lines in quasars enable us to "resolve" structure and kinematics of the broad line emitting region (BLR) thought to in- volve an accretion disk feeding a supermassive black hole. Interpretation of broad line measures within the 4DE1 formalism simplifies the apparent confusion among such data by contrasting and unifying properties of so-called high and low accreting Population A and B sources. H{\beta} serves as an estimator of black hole mass, Eddington ratio and source rest frame, the latter a valuable input for Civ{\lambda}1549 studies which allow us to isolate the blueshifted wind component. Optical and HST-UV spectra yield H{\beta} and Civ{\lambda}1549 spectra for low-luminosity sources while VLT-ISAAC and FORS and TNG-LRS provide spectra for high Luminosity sources. New high S/N data for Civ in high-luminosity quasars are presented here for comparison with the other previously published data. Comparison of H{\beta} and Civ{\lambda}1549 profile widths/shifts indicates that much of the emission from the two lines arise in regions with different structure and kinematics. Covering a wide range of luminosity and redshift shows evidence for a correlation between Civ{\lambda}1549 blueshift and source Eddington ratio, with a weaker trend with source luminosity (similar amplitude outflows are seen over 4 of the 5 dex luminosity range in our combined samples). At low luminosity (z < 0.7) only Population A sources show evidence for a significant outflow while at high luminosity the outflow signature begins to appear in Population B quasars as well.