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arXiv · 1911.06218

A Microlensing Accretion Disk Size Measurement in the Lensed Quasar WFI 2026-4536

Matthew A. Cornachione·Christopher W. Morgan·Martin Millon·Misty C. Bentz·Frederic Courbin·Vivien Bonvin·Emilio E. Falco
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Abstract

We use thirteen seasons of R-band photometry from the 1.2m Leonard Euler Swiss Telescope at La Silla to examine microlensing variability in the quadruply-imaged lensed quasar WFI 2026-4536. The lightcurves exhibit ${\sim}\,0.2\,\text{mag}$ of uncorrelated variability across all epochs and a prominent single feature of ${\sim}\,0.1\,\text{mag}$ within a single season. We analyze this variability to constrain the size of the quasar's accretion disk. Adopting a nominal inclination of 60$^\text{o}$, we find an accretion disk scale radius of $\log(r_s/\text{cm}) = 15.74^{+0.34}_{-0.29}$ at a rest-frame wavelength of $2043\,\unicode{xC5}$, and we estimate a black hole mass of $\log(M_{\text{BH}}/M_{\odot}) = 9.18^{+0.39}_{-0.34}$, based on the CIV line in VLT spectra. This size measurement is fully consistent with the Quasar Accretion Disk Size - Black Hole Mass relation, providing another system in which the accretion disk is larger than predicted by thin disk theory.

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Matthew A. Cornachione, Christopher W. Morgan, Martin Millon, Misty C. Bentz, Frederic Courbin, Vivien Bonvin, Emilio E. Falco. 2020-01-02. A Microlensing Accretion Disk Size Measurement in the Lensed Quasar WFI 2026-4536. https://doi.org/10.3847/1538-4357%2Fab557a

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