A Systematic Analysis of Fe II Emission in Quasars: Evidence for Inflow to the Central Black Hole

By Chen Hu, Jian-Min Wang, Luis C. Ho, Yan-Mei Chen, Haopeng Zhang, W. Bian, S. Xue. 2008

135 citations recorded by the source corpus.

Broad Fe II emission is a prominent feature of the optical and ultraviolet spectra of quasars. We report on a systematical investigation of optical Fe II emission in a large sample of 4037 z < 0.8 quasars selected from the Sloan Digital Sky Survey. We have developed and tested a detailed line-fitting technique, taking into account the complex continuum and narrow and broad emission-line spectra. Our primary goal is to quantify the velocity broadening and velocity shift of the Fe II spectrum in order to constrain the location of the Fe II-emitting region and its relation to the broad-line region. We find that the majority of quasars show Fe II emission that is redshifted, typically by ~400 km s−1, but up to 2000 km s−1, with respect to the systemic velocity of the narrow-line region or of the conventional broad-line region as traced by the Hβ line. Moreover, the line width of Fe II is significantly narrower than that of the broad component of Hβ. We show that the magnitude of the Fe II redshift correlates inversely with the Eddington ratio, and that there is a tendency for sources with redshifted Fe II emission to show red asymmetry in the Hβ line. These characteristics strongly suggest that Fe II originates from a location different from, and most likely exterior to, the region that produces most of Hβ. The Fe II-emitting zone traces a portion of the broad-line region of intermediate velocities whose dynamics may be dominated by infall.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/a68c23b61338995a48f6dd89589ee6f9d1417936

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Atomic and Molecular Physics, and Optics

Citations in the corpus

UNIFICATION OF LUMINOUS TYPE 1 QUASARS THROUGH C iv EMISSION (2010, background): “Some recent investigations have presented evidence for an infalling component of the BELR (Hu et al. 2008a, 2008b; Ferland et al. 2009).”
ANALYSIS OF OPTICAL Fe ii EMISSION IN A SAMPLE OF ACTIVE GALACTIC NUCLEUS SPECTRA (2010, background): “This is in agreement with the previous investigations (Popović et al. 2004; Hu et al. 2008b; Kuehn et al. 2008), but unlike the earlier investigations, we found a slight correlation with the width of VBLR.”
ESTIMATING BLACK HOLE MASSES IN ACTIVE GALACTIC NUCLEI USING THE Mg ii λ2800 EMISSION LINE (2009, background): “This trend has been noticed in the literature, but it was less prominent because of the narrower dynamical range in velocity covered in previous studies (e.g., Salviander et al. 2007; Hu et al. 2008).”
A CATALOG OF QUASAR PROPERTIES FROM SLOAN DIGITAL SKY SURVEY DATA RELEASE 7 (2010, unknown): “…Bachev et al. 2004; Dietrich & Hamann 2004; Baskin & Laor 2005; Kollmeier et al. 2006; Fine et al. 2006, 2008; Bonning et al. 2007; Salviander et al. 2007; Sulentic et al. 2007; Shen et al. 2008a,b; Hu et al. 2008a,b; Zamfir et al. 2010; Wang et al. 2009b; Wu et al. 2009; Dong et al. 2009b,a).”
What broad emission lines tell us about how active galactic nuclei work (2009, background): “Understanding how the very strong optical Fe II emission seen in AGNs is produced has been a longstanding problem (see Baldwin et al. 2004; Joly et al. 2008; Hu et al. 2008; Kuehn et al. 2008; Verner et al. 2009; Dong et al. 2009 for recent discussions).”
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. IX. 10 New Observations of Reverberation Mapping and Shortened Hβ Lags (2018, methodology): “In SEAMBH2013–2014, we fitted the spectra of all the quasars in Data Release 7 of the Sloan Digital Sky Survey (SDSS) using the fitting procedure in Hu et al. (2008a, 2008b), then estimated their BH masses and accretion rates by applying the normal RHβ–L5100 relation in Bentz et al. (2013).”
Black Hole Growth to z = 2 - I: Improved Virial Methods for Measuring M_BH and L/L_Edd (2012, background): “However, the differences in the main derived parameters (L5100 and FWHM(Hβ )) are negligible (see Hu et al. 2008; Marziani & Sulentic 2012).”