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A Description of Quasar Variability Measured Using Repeated SDSS and POSS Imaging

MacLeod, Chelsea L. and Ivezić, Željko and Sesar, Branimir and de Vries, Wim and Kochanek, Christopher S. and Kelly, Brandon C. and Becker, Andrew C. and Lupton, Robert H. and Hall, Patrick B. and Richards, Gordon T. and Anderson, Scott F. and Schneider, Donald P. (2012) A Description of Quasar Variability Measured Using Repeated SDSS and POSS Imaging. Astrophysical Journal, 753 (2). Art. No. 106. ISSN 0004-637X.

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We provide a quantitative description and statistical interpretation of the optical continuum variability of quasars. The Sloan Digital Sky Survey (SDSS) has obtained repeated imaging in five UV-to-IR photometric bands for 33,881 spectroscopically confirmed quasars. About 10,000 quasars have an average of 60 observations in each band obtained over a decade along Stripe 82 (S82), whereas the remaining ~25,000 have 2-3 observations due to scan overlaps. The observed time lags span the range from a day to almost 10 years, and constrain quasar variability at rest-frame time lags of up to 4 years, and at rest-frame wavelengths from 1000 Å to 6000 Å. We publicly release a user-friendly catalog of quasars from the SDSS Data Release 7 that have been observed at least twice in SDSS or once in both SDSS and the Palomar Observatory Sky Survey, and we use it to analyze the ensemble properties of quasar variability. Based on a damped random walk (DRW) model defined by a characteristic timescale and an asymptotic variability amplitude that scale with the luminosity, black hole mass, and rest wavelength for individual quasars calibrated in S82, we can fully explain the ensemble variability statistics of the non-S82 quasars such as the exponential distribution of large magnitude changes. All available data are consistent with the DRW model as a viable description of the optical continuum variability of quasars on timescales of ~5-2000 days in the rest frame. We use these models to predict the incidence of quasar contamination in transient surveys such as those from the Palomar Transient Factory and Large Synoptic Survey Telescope.

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Sesar, Branimir0000-0002-0834-3978
Additional Information:© 2012 American Astronomical Society. Received 2011 December 2; accepted 2012 May 3; published 2012 June 19. We acknowledge support by NSF Grant AST-0807500 to the University of Washington, and NSF Grant AST-0551161 to LSST for design and development activity. B.S. would like to acknowledge NSF grant AST-0908139 awarding to Judy Cohen for partial support. C.S.K. is supported by NSF Grant AST-1009756. We thank the referee for a thorough review and suggestions which led to an improved manuscript. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington.
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Subject Keywords:quasars: general
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Official Citation:A Description of Quasar Variability Measured Using Repeated SDSS and POSS Imaging Chelsea L. MacLeod et al. 2012 ApJ 753 106
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:32797
Deposited By: Jason Perez
Deposited On:01 Aug 2012 14:51
Last Modified:22 Nov 2017 17:17

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