Accretion Disk Size Measurement and Time Delays in the Lensed Quasar WFI 2033-4723

Abstract

We present 13 seasons of R-band photometry of the quadruply lensed quasar WFI 2033-4723 from the 1.3 m SMARTS telescope at CTIO and the 1.2 m Euler Swiss Telescope at La Silla, in which we detect microlensing variability of ∼0.2 mag on a timescale of ∼6 years. Using a Bayesian Monte Carlo technique, we analyze the microlensing signal to obtain a measurement of the size of this system’s accretion disk of {log}({r}_s/{cm})={15.86}_-0.27^+0.25 at λ _rest = 2481 Å, assuming a 60° inclination angle. We confirm previous measurements of the BC and AB time delays, and we obtain a tentative measurement of the delay between the closely spaced A1 and A2 images of {{Δ }}{t}_{{A}1{{A}}2}={t}_{{A}1}-{t}_{{A}2}=-{3.9}_-2.2^+3.4 days. We conclude with an update to the Quasar Accretion Disk Size-Black Hole Mass Relation, in which we confirm that the accretion disk size predictions from simple thin disk theory are too small.