Exploring the diversity of Type 1 active galactic nuclei identified in SDSS-IV/SPIDERS. Issue 3 (8th January 2020)

• Record Type: Journal Article
• Authors: Wolf, Julien; Salvato, Mara; Coffey, Damien; Merloni, Andrea; Buchner, Johannes; Arcodia, Riccardo; Baron, Dalya; Carrera, Francisco J; Comparat, Johan; Schneider, Donald P; Nandra, Kirpal
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 492:Issue 3(2020)
• Page Start: 3580
• Page End: 3601
• Publication Date: 2020-01-08
• Subjects: accretion, accretion discs -- techniques: spectroscopic -- galaxies: active -- galaxies: nuclei; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa018
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present a statistical analysis of the optical properties of an X-ray-selected Type 1 active galactic nucleus (AGN) sample, using high signal-to-noise ratio (S/N>20) spectra of the counterparts of the ROSAT /2RXS sources in the footprint of the SDSS-IV/SPIDERS (Spectroscopic IDentification of eROSITA Sources) programme. The final sample contains 2100 sources. It significantly extends the redshift and luminosity ranges ( z ∼ 0.01–0.80 and $L_{\rm 0.1\!-\!2.4 \, keV} \sim \rm 2.0 \times 10^{41}\!-\!1.0 \times 10^{46} \, \, erg \, s^{-1}$ ) used so far in this kind of analysis. By means of a principal component analysis, we derive eigenvector (EV) 1 and 2 in an eleven-dimensional optical and X-ray parameter space, which are consistent with previous results. The validity of the correlations of the Eddington ratio L/L Edd with EV1 and the black hole mass with EV2 is strongly confirmed. These results imply that L/L Edd and black hole mass are related to the diversity of the optical properties of Type 1 AGNs. Investigating the relation of the width and asymmetry of H β and the relative strength of the iron emission $r_{\rm Fe\, \small{II}}$, we show that our analysis supports the presence of a distinct kinematic region: the very broad line region. Furthermore, comparing sources with a red-asymmetric broad H β emission line to sources for which it is blue asymmetric, we find an intriguing difference in the correlation of the $\rm Fe\, \small{II}$ and the continuum emission strengths. We show that this contrasting behaviour is consistent with a flattened, stratified model of the broad-line region, in which the $\rm Fe\, \small{II}$ -emitting region is shielded from the central source.