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[78.06] Spectral Variability of Quasars in the Sloan Digital Sky Survey

B.C. Wilhite (University of Chicago), D.E. Vanden Berk (University of Pittsburgh), Sloan Digital Sky Survey Collaboration

During the normal course of operations, the Sloan Digital Sky Survey has taken repeat spectral observations of ~150 plates over the last three and a half years. This has resulted in multiple epoch spectroscopy for some 5000 quasars with time separations ranging from days to over a year. With this sample, we have identified of order a few hundred quasars that we deem to have varied significantly between observations (with respect to assumed non-variable stars on the same plates). Using these spectra, we create an ensemble difference spectrum covering rest-frame wavelengths from the ultraviolet to the near infrared. The difference spectrum is stronger at lower wavelengths, verifying that quasars are bluer in their bright phase than in their faint phase. Additionally, this difference spectrum is inconsistent with a single-temperature blackbody, indicating that accretion disk ``hot spots'' are not likely to be the cause of variability.

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.