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Paper: Eigenspectra of the SDSS DR1 Quasars
Volume: 311, AGN Physics with the Sloan Digital Sky Survey
Page: 17
Authors: Yip, C.-W.; Connolly, A.J.; Vanden Berk, D.E.; Ma, Z.; Frieman, J.A.; SubbaRao, M.; Szalay, A.S.
Abstract: We construct eigenspectra from the DR1 quasars in the SDSS using the Karhunen-Loève (KL) transform (or Principal Component Analysis, PCA) in different redshift and luminosity bins. We find that the quasar spectra can be classified, by the first two eigenspectra, into a continuous sequence in the variation of the spectral slope. We also find a dependence on redshift and luminosity in the eigencoefficients. The dominant redshift effect is the evolution of the blended optical Fe II emission and the Balmer continuum (the "small-bump", λrest ≈ 2000-4000Å), while the luminosity effect is related to the Baldwin effect. Correlations among several major broad emission lines are found, including the well-known "Eigenvector 1".
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