Main trends of the quasar main sequence -- effect of viewing angle

Abstract

We address the effect of the viewing angle of the accretion disk plane and the geometry of the broad-line region (BLR) with the goal of interpreting the distribution of quasars along the main sequence (MS). We utilize photoionization code CLOUDY to model the BLR FeII emission, incorporating the grossly underestimated role of the form factor (f). We recover the dependence of the strength of the FeII emission in the optical (R${}_{\mathrm{FeII}}$) on L${}_{\mathrm{bol}}$/L${}_{\mathrm{Edd}}$ ratio and related observational trends - as a function of the spectral energy distribution (SED) shape, cloud density, composition and intra-cloud dynamics, assumed following prior observational constraints. With this approach, we are now able to explain the diversity of quasars and the change of the quasar properties along the Main Sequence (MS). Our approach also explains the rarity of the highest FeII emitters known as the extreme xA sources and can be used as a predictive tool in future reverberation mapping studies of Type-1 AGNs. This approach further justifies the use of quasars as `cosmological probes'.

arXiv comment15 pages, 5 figures; Contributions of the Astronomical Observatory Skalnaté Pleso (CAOSP) as a Special Issue "Spectral Line Shapes in Astrophysics and Related Topics"

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Cited by in corpus (6)

• High metal content of highly accreting quasars
• Quasar main sequence in the UV plane
• Unveiling the quasar main sequence: illuminating the complexity of active galactic nuclei and their evolution
• The CaFe Project: Optical FeII and Near-Infrared Ca II triplet emission in active galaxies. II. The driver(s) of the Ca II and Fe II and its potential use as a chemical clock
• Orientation and accretion in a representative sample of active galactic nuclei
• FeII strength in NLS1s -- dependence on the viewing angle and FWHM