Searching for the Physical Drivers of the Eigenvector 1 Correlation Space

By P. Marziani, J. Sulentic, T. Zwitter, D. Dultzin-Hacyan, M. Calvani. 2001

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We recently discussed an Eigenvector 1 (E1) parameter space that provides optimal discrimination between the principal classes of broad-line active galactic nuclei (AGNs). In this paper we begin a search for the most important physical parameters that are likely to govern correlations and data point distribution in E1 space. We focus on the principal optical parameter plane involving the width of the Hβ broad component [FWHM(HβBC)] and the equivalent width ratio between the Fe II blend at 4570 Å and HβBC. We show that the observed correlation for radio-quiet sources can be accounted for if it is primarily driven by the ratio of AGN luminosity to black hole mass (L/M ∝ Eddington ratio) convolved with source orientation. L/M apparently drives the radio-quiet correlation only for FWHM(Hβ) ≲ 4000 km s-1, which includes narrow-line Seyfert 1 galaxies and can be said to define an AGN "main sequence." Source orientation plays an increasingly important role as FWHM(HβBC) increases. We also argue that AGNs lying outside the radio-quiet main sequence, and specifically those with optical Fe II much stronger than expected for a given FWHM(HβBC), may all be broad absorption line QSOs.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/4d6c549425946bff85073a25f7af9714bb7252ce

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Citations in the corpus

An Optical Spectroscopic Atlas of Low-Redshift Active Galactic Nuclei (2003, methodology): “Population A and population B sources were modeled using different values for the ionization parameter and electron density: logU ¼ 2, log ne ¼ 11 for population A, and logU ¼ 1, log ne ¼ 9:5 for population B (Marziani et al. 2001).”
A Systematic Analysis of Fe II Emission in Quasars: Evidence for Inflow to the Central Black Hole (2008, methodology): “…statistical measures of AGN correlations, such as the so-called eigenvector 1 derived from principal component analysis, which is believed to be driven by some fundamental property such as mass accretion rate (e.g., Boroson & Green 1992; Sulentic et al. 2000a, 2000b;Marziani et al. 2001, 2003a).”
C IV λ1549 as an Eigenvector 1 Parameter for Active Galactic Nuclei (2007, background): “Exploration of possible physical drivers of source occupation /correlation in 4DE1 (Marziani et al. 2001, 2003b; Boroson 2002) suggest that it is primarily driven by the luminosity to black hole mass (MBH) ratio which is proportional to the Eddington ratio (Lbol /LEdd) with Population A sources…”
Radio-loud Narrow-Line Type 1 Quasars (2006, background): “The disk emission of FeII is also anisotropic and FeII emission is strongest when the disk is viewed face-on (e.g., Miller et al. 1993, Marziani et al. 01).”
A Comprehensive Study of 2000 Narrow Line Seyfert 1 Galaxies from the Sloan Digital Sky Survey. I. The Sample (2006, background): “…basic physical parameters of the black hole accretion disk such as the black hole mass and accretion rate, or geometrical parameters such as the viewing angle (Boroson & Green 1992; Boller et al. 1996;Wang et al. 1996; Laor et al. 1997; Sulentic et al. 2000; Marziani et al. 2001; Xu et al. 2003).”
Average Quasar Spectra in the Context of Eigenvector 1 (2002, background): “B (Marziani et al. 2001).”
ANALYSIS OF OPTICAL Fe ii EMISSION IN A SAMPLE OF ACTIVE GALACTIC NUCLEUS SPECTRA (2010, background): “Some of physical properties which may influence these correlations are the Eddington ratio (L/LEdd; Boroson & Green 1992; Baskin & Laor 2004), black hole mass (MBH), and inclination angle (Miley & Miller 1979; Wills & Browne 1986; Marziani et al. 2001).”