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D. Vanden Berk (Penn State), B. Wilhite (Illinois), R. Kron (Chicago), Z. Ivezic (Washington), N. Pereyra (Pittsburgh), SDSS Collaboration
Quasar variability is a long-known but poorly understood phenomenon. The Sloan Digital Sky Survey, while not designed with variability studies in mind, has recently provided a wealth of knowledge on the photometric and spectroscopic variability of quasars. Photometric variability has been studied by comparing imaging data in mulitply-scanned areas, comparing SDSS photometry with data from earlier photographic surveys, and comparing imaging and spectroscopic photometry. These complementary approaches have used tens of thousands of SDSS quasars to characterize variability as a function of rest-frame time lag, luminosity, wavelength, and redshift, and the dependence of variability on radio, X-ray, and broad absorption line classes. Multiple spectroscopic observations of thousands of SDSS quasars has also provided new insights into quasar variability at the resolution of angstroms. At this level of detail, continuum and emission line variability have been separated and studied independently. The results so far lend strong evidence for accretion disk processes as the primary source of quasar variability. Spectroscopic variations also provide a means for estimating quasar physical parameters, such as disk temperature, black hole mass, accretion rate, and geometry.
Funding for the Sloan Digital Sky Survey (SDSS) has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, and the Max Planck Society.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.