The Sloan Digital Sky Survey Reverberation Mapping Project: accretion disk sizes from continuum lags

Y. Homayouni, Jonathan R. Trump, C. J. Grier, Yue Shen, D. A. Starkey, W. N. Brandt, G. Fonseca Alvarez, P. B. Hall, Keith Horne, Karen Kinemuchi, Jennifer I-Hsiu Li, Ian D. McGreer, Mouyuan Sun, L. C. Ho, D. P. Schneider

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17 Citations (Scopus)


We present accretion disk structure measurements from continuum lags in the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. Lags are measured using the JAVELIN software from the first-year SDSS-RM g and i photometry, resulting in well-defined lags for 95 quasars, 33 of which have lag S/N > 2σ. We also estimate lags using the ICCF software and find consistent results, though with larger uncertainties. Accretion disk structure is fit using a Markov chain Monte Carlo approach, parameterizing the measured continuum lags as a function of disk size normalization, wavelength, black hole mass, and luminosity. In contrast with previous observations, our best-fit disk sizes and color profiles are consistent (within 1.5σ) with the Shakura & Sunyaev analytic solution. We also find that more massive quasars have larger accretion disks, similarly consistent with the analytic accretion disk model. The data are inconclusive on a correlation between disk size and continuum luminosity, with results that are consistent with both no correlation and the Shakura & Sunyaev expectation. The continuum lag fits have a large excess dispersion, indicating that our measured lag errors are underestimated and/or our best-fit model may be missing the effects of orientation, spin, and/or radiative efficiency. We demonstrate that fitting disk parameters using only the highest-S/N lag measurements biases best-fit disk sizes to be larger than the disk sizes recovered using a Bayesian approach on the full sample of well-defined lags.
Original languageEnglish
Article number126
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 1 Aug 2019


  • Accretion, accretion disks
  • Galaxies: active
  • Galaxies: nuclei
  • Quasars: general


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