Black Hole Mass and Eddington Ratio as Drivers for the Observable Properties of Radio‐loud and Radio‐quiet QSOs

Abstract

Recent studies of black holes in the nuclei of both active and normal galaxies have yielded relationships that permit a physical interpretation of the principal components of the spectra of QSOs. It is shown that principal component (or eigenvector) 1 (PC1) is driven predominantly by L/L{Edd}, and principal component 2 (PC2) is driven by luminosity or accretion rate. This results in a PC2 vs. PC1 diagram in which lines of constant black hole mass are diagonal. Using a sample consisting of the low-redshift PG objects supplemented by 46 radio-loud QSOs, it is shown that such a diagram effectively distinguishes radio-loud from radio-quiet as well as demonstrating that both narrow-line Seyfert 1s and broad absorption-line QSOs (BALQSOs) lie at the high L/LEdd} extreme, though these two types of objects are well separated in the PC2 direction. The very few radio-loud BALQSOs known fall in the region expected to be populated by such objects. Finally, a simple picture that ties together physical parameters and classification of AGN is presented.