Strong Chromatic Microlensing in He0047–1756 and Sdss1155+6346

We use spectra of the double lensed quasars HE0047-1756 and SDSS1155+6346 to study their unresolved structure through the impact of microlensing. There is no significant evidence of microlensing in the emission line profiles except for the Lyα line of SDSS1155+6346, which shows strong differences in the shapes for images A and B. However, the continuum of the B image spectrum in SDSS1155+6346 is strongly contaminated by the lens galaxy and these differences should be considered with caution. Using the flux ratios of the emission lines for image pairs as a baseline to remove macro-magnification and extinction, we have detected strong chromatic microlensing in the continuum measured by CASTLES (http://www.cfa.harvard.edu/castles/), in both lens systems, with amplitudes 0.09 (λ 16000) |Δ m | 0.8 (λ 5439) for HE0047-1756, and 0.2 (λ 16000) |Δ m | 0.8 (λ 5439) for SDSS1155+6346. Using magnification maps to simulate microlensing, and modeling the accretion disk as a Gaussian source (I ∝ exp(-R²/2r²ₛ)) of size rₛ ∝ λᵖ we find, rₛ = 2.5-1.4+3.0 √M/0.3M_ light days and p = 2.3 ± 0.8, at the rest frame for λ = 2045, for HE0047-1756 (log prior), and rₛ = 5.5-3.3+8.2 √M/0.3M_ light days and p = 1.5 ± 0.6 at the rest frame of λ = 1398, for SDSS1155+6346 (log prior). Contrary to other studied lens systems, the chromaticity detected in HE0047-1756 and SDSS1155+6346 is large enough to fulfill the thin disk prediction. The inferred sizes, however, are very large compared to the predictions of this model, especially in the case of SDSS1155+6346.