Strong [O III] objects among sdss broad-line active galaxies

We present the results of a spectral principal component analysis on 9046 broad-line active galactic nuclei from the Sloan Digital Sky Survey. We examine correlations between spectral regions within various eigenspectra (e.g., between Fe II strength and Hβ width) and confirm that the same trends are apparent in spectral measurements, as validation of our technique. Because we found that our sample had a large range in the equivalent width of [O III] λ5007, we divided the data into three subsets based on [O III] strength. Of these, only in the sample with the weakest equivalent width of [O III] were we able to recover the known correlation between [O III] strength and full width at half maximum of Hβ and their anticorrelation with Fe II strength. At the low luminosities considered here (L _5100Å of 10⁴²- 10⁴⁶ erg s^-1), interpretation of the principal components is considerably complicated particularly because of the wide range in [O III] equivalent width. We speculate that variations in the covering factor are responsible for this wide range in [O III] strength.