An Active Galactic Nucleus Sample with High X‐Ray–to–Optical Flux Ratio from RASS. II. Optical Emission Line Properties of Seyfert 1–Type Active Galactic Nuclei

Abstract

This work studies the optical emission line properties of a sample of 155 low-redshift bright X-ray selected ROSAT Seyfert~1 type AGN for which adequate signal-to-noise ratio spectroscopic observations are available. We measured emission line properties by performing multi-component fits to the emission line profiles, covering the effect of blended iron emission. We also obtained continuum parameters, including 250eV X-ray luminosities derived from the ROSAT database. In addition, the measured properties are gathered for a correlation analysis, which confirms the well-known relations between the strengths of Fe~II, [O III] emission and the X-ray slope. We also detect striking correlations between H$\beta$ redshift (or blueshift), flux ratios of Fe `II to H$\beta$ broad component and [O III] to H$\beta$ narrow component. These trends are most likely driven by the Eddington ratio.