A description of quasar variability measured using repeated SDSS and poss imaging

Chelsea L. MacLeod, Željko Ivezić, Branimir Sesar, Wim De Vries, Christopher S. Kochanek, Brandonc Kelly, Andrew C. Becker, Robert H. Lupton, Patrick B. Hall, Gordon T. Richards, Scott F. Anderson, Donald P. Schneider

Research output: Contribution to journalReview article

114 Citations (Scopus)

Abstract

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 10years, and constrain quasar variability at rest-frame time lags of up to 4years, and at rest-frame wavelengths from 1000Å to 6000Å. 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 5-2000days 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.

Original languageEnglish (US)
Article number106
JournalAstrophysical Journal
Volume753
Issue number2
DOIs
StatePublished - Jul 10 2012

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quasars
random walk
wavelength
timescale
time lag
continuums
observatory
industrial plants
wavelengths
catalogs
observatories
contamination
incidence
luminosity
statistics
telescopes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

MacLeod, Chelsea L. ; Ivezić, Željko ; Sesar, Branimir ; De Vries, Wim ; Kochanek, Christopher S. ; Kelly, Brandonc ; Becker, Andrew C. ; Lupton, Robert H. ; Hall, Patrick B. ; Richards, Gordon T. ; Anderson, Scott F. ; Schneider, Donald P. / A description of quasar variability measured using repeated SDSS and poss imaging. In: Astrophysical Journal. 2012 ; Vol. 753, No. 2.
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abstract = "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 10years, and constrain quasar variability at rest-frame time lags of up to 4years, and at rest-frame wavelengths from 1000{\AA} to 6000{\AA}. 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 5-2000days 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.",
author = "MacLeod, {Chelsea L.} and Željko Ivezić and Branimir Sesar and {De Vries}, Wim and Kochanek, {Christopher S.} and Brandonc Kelly and Becker, {Andrew C.} and Lupton, {Robert H.} and Hall, {Patrick B.} and Richards, {Gordon T.} and Anderson, {Scott F.} and Schneider, {Donald P.}",
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MacLeod, CL, Ivezić, Ž, Sesar, B, De Vries, W, Kochanek, CS, Kelly, B, Becker, AC, Lupton, RH, Hall, PB, Richards, GT, Anderson, SF & Schneider, DP 2012, 'A description of quasar variability measured using repeated SDSS and poss imaging', Astrophysical Journal, vol. 753, no. 2, 106. https://doi.org/10.1088/0004-637X/753/2/106

A description of quasar variability measured using repeated SDSS and poss imaging. / MacLeod, Chelsea L.; Ivezić, Željko; Sesar, Branimir; De Vries, Wim; Kochanek, Christopher S.; Kelly, Brandonc; Becker, Andrew C.; Lupton, Robert H.; Hall, Patrick B.; Richards, Gordon T.; Anderson, Scott F.; Schneider, Donald P.

In: Astrophysical Journal, Vol. 753, No. 2, 106, 10.07.2012.

Research output: Contribution to journalReview article

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T1 - A description of quasar variability measured using repeated SDSS and poss imaging

AU - MacLeod, Chelsea L.

AU - Ivezić, Željko

AU - Sesar, Branimir

AU - De Vries, Wim

AU - Kochanek, Christopher S.

AU - Kelly, Brandonc

AU - Becker, Andrew C.

AU - Lupton, Robert H.

AU - Hall, Patrick B.

AU - Richards, Gordon T.

AU - Anderson, Scott F.

AU - Schneider, Donald P.

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N2 - 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 10years, and constrain quasar variability at rest-frame time lags of up to 4years, and at rest-frame wavelengths from 1000Å to 6000Å. 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 5-2000days 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.

AB - 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 10years, and constrain quasar variability at rest-frame time lags of up to 4years, and at rest-frame wavelengths from 1000Å to 6000Å. 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 5-2000days 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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MacLeod CL, Ivezić Ž, Sesar B, De Vries W, Kochanek CS, Kelly B et al. A description of quasar variability measured using repeated SDSS and poss imaging. Astrophysical Journal. 2012 Jul 10;753(2). 106. https://doi.org/10.1088/0004-637X/753/2/106