The Sloan Digital Sky Survey Reverberation Mapping Project: Accretion Disk Sizes from Continuum Lags

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 l...

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Bibliographic Details
Published in:The Astrophysical journal 2019-08, Vol.880 (2), p.126
Main Authors: Homayouni, Y., Trump, Jonathan R., Grier, C. J., Shen, Yue, Starkey, D. A., Brandt, W. N., Alvarez, G. Fonseca, Hall, P. B., Horne, Keith, Kinemuchi, Karen, Li, Jennifer I-Hsiu, McGreer, Ian D., Sun, Mouyuan, Ho, L. C., Schneider, D. P.
Format: Article
Language:English
Subjects:
Accretion disks
accretion, accretion disks
Astrophysics
Bayesian analysis
Computer simulation
Correlation
Digital mapping
Exact solutions
galaxies: active
galaxies: nuclei
Luminosity
Markov chains
Quasars
quasars: general
Reverberation
Sky surveys (astronomy)
Software
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Summary: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 > 2 . 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 1.5 ) 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.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ab2638