A Complete Sample of Soft X-ray Selected AGN: II. Statistical Analysis

Direct correlations and a Principal Component Analysis (PCA) are presented for a complete sample of 110 soft X-ray selected AGN of which about half are Narrow-Line Seyfert 1 galaxies (NLS1s). The direct correlation analyses show that narrower FWHM(Hβ) correlates with steeper X-ray spectrum, stronger optical FeII emission, weaker [OIII] emission and stronger short-term X-ray variability. This direct correlation analysis and the PCA confirm the Boroson & Green (1992) Eigenvector 1 relationship for AGN: FeII strength anti-correlates with [OIII] line strength. Eigenvector 1 is well-correlated with the Eddington luminosity ratio L/LEdd while Eigenvector 2 shows a very good correlation with the mass of the central black hole MBH and the mass accretion rate Ṁ . The Eddington ratio L/LEdd correlates with the X-ray spectral index αX and the black home mass MBH anti-correlates with the X-ray variability χ /ν. The Eddington ration L/LEdd may be interpreted as the age of an AGN: AGN with steep X-ray spectra, strong FeII, and weak [OIII] are AGN in an early phase of their evolution. In this hypothesis NLS1s are young AGN. Subject headings: galaxies: active quasars:general