Dissecting the quasar main sequence: insight from host galaxy properties

Abstract

The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical FeII strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/L_Edd) of the black hole (BH) accretion. Shen & Ho demonstrated with quasar clustering analysis that the average BH mass decreases with increasing FeII strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion sigma* (hence the BH mass via the M-sigma* relation) from decomposed host spectra in low-redshift Sloan Digital Sky Survey quasars. We found that at fixed quasar luminosity, sigma* systematically decreases with increasing FeII strength, confirming that Eddington ratio increases with FeII strength. We also found that at fixed luminosity and FeII strength, there is little dependence of sigma* on the broad Hbeta FWHM. These new results reinforce the framework put forward by Shen & Ho that Eddington ratio and orientation govern most of the diversity seen in broad-line quasar properties.

ApJL in press; 5 pages and 4 figures

References in corpus (6)

• A Catalog of Quasar Properties from SDSS DR7
• Biases in Virial Black Hole Masses: An SDSS Perspective
• The diversity of quasars unified by accretion and orientation
• CIV 1549 as an Eigenvector 1 Parameter for Active Galactic Nuclei
• Self-shadowing Effects of Slim Accretion Disks in Active Galactic Nuclei: Diverse Appearance of the Broad-line Region
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• Extreme quasars as distance indicators in cosmology
• The physical driver of the optical Eigenvector 1 in Quasar Main Sequence
• Evaluating and Improving the Redshifts of z>2.2 Quasars