2001/09/19 by Todd A. Boroson · 19 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/324486
published as Astrophys.J.565:78-85,2002 · 21 pages including 7 figures, accepted for publication in Ap.J
arxiv created 2001/09/19 · openalex publication_date 2002/01/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
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 accretion rate. This results in a PC2 versus PC1 diagram in which lines of constant black hole mass are diagonal. Using a sample consisting of the low-redshift PG objects supplemented by 75 radio-loud QSOs, it is shown that such a diagram effectively distinguishes radio-loud from radio-quiet objects and demonstrates that both narrow-line Seyfert 1 galaxies and broad absorption line QSOs lie at the high L / L Edd extreme, although these two types of objects are well separated in the PC2 direction. A simple picture that ties together physical parameters (black hole mass and Eddington ratio) and classification of active galactic nuclei is presented. Based on the location of core-dominated and lobe-dominated radio-loud QSOs, orientation can be modeled as a third parameter in this scheme, implying an enhancement in the radio flux of core-dominated objects.