Quasar accretion disk sizes from continuum reverberation mapping from the Dark Energy Survey

Mudd, D, Martini, P, Zu, Y, Kochanek, C, Peterson, B M, Kessler, R, Davis, T M, Hoormann, J K, King, A, Lidman, C, Romer, A K and DES Collaboration, (2018) Quasar accretion disk sizes from continuum reverberation mapping from the Dark Energy Survey. Astrophysical Journal, 862 (123). pp. 1-13. ISSN 0004-637X

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We present accretion disk size measurements for 15 luminous quasars at 0.7�z�1.9 derived from griz light
curves from the Dark Energy Survey. We measure the disk sizes with continuum reverberation mapping using two methods, both of which are derived from the expectation that accretion disks have a radial temperature gradient and the continuum emission at a given radius is well described by a single blackbody. In the first method we measure the relative lags between the multiband light curves, which provides the relative time lag between shorter and longer wavelength variations. From this, we are only able to constrain upper limits on disk sizes, as many are consistent with no lag the 2σ level. The second method fits the model parameters for the canonical thin disk directly rather than solving for the individual time lags between the light curves. Our measurements demonstrate good agreement with the sizes predicted by this model for accretion rates between 0.3 and 1 times the Eddington rate. Given our large uncertainties, our measurements are also consistent with disk size measurements from gravitational microlensing studies of strongly lensed quasars, as well as other photometric reverberation mapping results, that find disk sizes that are a factor of a few (∼3) larger than predictions.

Item Type: Article
Keywords: accretion, accretion disks – galaxies: active – quasars: general
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Astronomy Centre
Subjects: Q Science > QB Astronomy
Depositing User: Jodie Bacon
Date Deposited: 24 Sep 2018 08:50
Last Modified: 24 Sep 2018 08:53
URI: http://srodev.sussex.ac.uk/id/eprint/78911

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