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

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posted on 2023-06-09, 15:10 authored by D Mudd, P Martini, Y Zu, C Kochanek, B M Peterson, R Kessler, T M Davis, J K Hoormann, A King, C Lidman, Kathy RomerKathy Romer, DES Collaboration
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 2s 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.

History

Publication status

  • Published

File Version

  • Published version

Journal

Astrophysical Journal

ISSN

0004-637X

Publisher

American Astronomical Society

Issue

123

Volume

862

Page range

1-13

Department affiliated with

  • Physics and Astronomy Publications

Research groups affiliated with

  • Astronomy Centre Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2018-09-24

First Open Access (FOA) Date

2018-09-24

First Compliant Deposit (FCD) Date

2018-09-21

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