2004AJ....127.1799G

Direct correlations and a principal component analysis (PCA) are presented for a complete sample of 110 soft X-ray-selected AGNs, of which about half are narrow-line Seyfert 1 galaxies (NLS1's). The direct correlation analyses show that narrower FWHM(Hβ) correlates with steeper X-ray spectrum, stronger optical Fe II emission, weaker [O III] emission and stronger short-term X-ray variability. This direct correlation analysis and the PCA confirm the Boroson & Green (1992) eigenvector 1 relationship for AGNs: Fe II strength anticorrelates with [O III] line strength. Eigenvector 1 is well correlated with the Eddington luminosity ratio L/L_Edd, while eigenvector 2 shows a very good correlation with the mass of the central black hole M_BHand the mass accretion rate M{dot}. The Eddington ratio L/L_Eddcorrelates with the X-ray spectral index α_X and the black home mass M_BHanticorrelates with the X-ray variability χ²/ν. The Eddington ratio L/L_Eddmay be interpreted as the age of an AGN: AGNs with steep X-ray spectra, strong Fe II, and weak [O III] are AGNs in an early phase of their evolution. In this hypothesis, NLS1's are young AGNs.