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 1.3m SMARTS telescope at CTIO and the 1.2m Euler Swiss Telescope at La Silla, in which we detect microlensing variability of $\sim 0.2$ mags on a timescale of $\sim$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 $\log (r_s/\mathrm{cm})=15.86_{-0.27}^{+0.25}$ at $\hat{I}{»}_{rest}=2481\tilde{\mathrm{A}}$, assuming a $60^{\circ }$ 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 $\hat{I}”t_{A1A2}=t_{A1}-t_{A2}=-3.9_{-2.2}^{+3.4}$ 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.

20 pages, 9 figures, Accepted by ApJ