Exploring the Diversity of Type 1 Active Galactic Nuclei Identified in
  SDSS-IV/SPIDERS
  We present a statistical analysis of the optical properties of an X-ray
selected Type 1 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 ($\rm z \sim 0.01 - 0.80$ and $\rm L_{0.1-2.4 \,keV}$ ~
$\rm 2.0 \times 10^{41}$ - $\rm 1.0 \times 10^{46} \, erg s^{-1}$ ) 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 $\rm L/L_{Edd}$ with EV1 and the black hole
mass with EV2 are strongly confirmed These results imply that $\rm L/L_{Edd}$
and black hole mass are related to the diversity of the optical properties of
Type 1 AGN. Investigating the relation of the width and asymmetry of $\rm
H\beta$ and the relative strength of the iron emission $\rm r_{FeII}$ , 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 $\rm H\beta$ emission line to sources for which it is blue-asymmetric, we
find an intriguing difference in the correlation of the FeII 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 FeII
emitting region is shielded from the central source.
