2020ApJ...905....7C

We present a microlensing analysis of updated light curves in three filters, the g-band, r-band, and H-band, for the gravitationally lensed quasars Q0957+561 and SBS0909+532. Both systems display prominent microlensing features which we analyze using our Bayesian Monte Carlo technique to constrain the quasar continuum emission region sizes in each band. We report sizes as half-light radii scaled to a 60° inclination angle. For Q0957+561 we measure log(r_1/2/cm)=16.54_–0.33^+0.33, 16.66_–0.62^+0.37, and 17.37_–0.40^+0.49 in g-, r-, and H-band, respectively. For SBS0909+532 we measure log(r_1/2/cm)=15.83_–0.33^+0.33, 16.21_–0.62^+0.37, and 17.90_–0.63^+0.61 in the g-, r-, and H-band respectively. With size measurements in three bands spanning the quasar rest frame ultraviolet to optical, we can place constraints on the scaling of accretion disk size with wavelength, r∝λ^1/β^. In a joint analysis of both systems we find a slope shallower than that predicted by thin disk theory, β=0.35_–0.08^+0.16, consistent with other constraints from multi-epoch microlensing studies.