Strong Chromatic Microlensing in HE0047–1756 and SDSS1155+6346

Rojas, K.; Motta, V.; Mediavilla, E.; Falco, E.; Jiménez-Vicente, J.; Muñoz, J. A.
Bibliographical reference

The Astrophysical Journal, Volume 797, Issue 1, article id. 61, 7 pp. (2014).

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12
2014
Description
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 (www.cfa.harvard.edu/castles/) in both lens systems, with amplitudes 0.09(λ16000) <~ |Δm| <~ 0.8(λ5439) for HE0047–1756, and 0.2(λ16000) <~ |Δm| <~ 0.8(λ5439) for SDSS1155+6346. Using magnification maps to simulate microlensing and modeling the accretion disk as a Gaussian source (I vprop exp(–R 2/2r ^2_s)) of size r s vprop λ p , we find r s = 2.5-1.4+3.0 \sqrt{M/0.3Mȯ } lt-day and p = 2.3 ± 0.8 at the rest frame for λ = 2045 for HE0047–1756 (log prior) and r s = 5.5-3.3+8.2 \sqrt{M/0.3Mȯ } lt-day 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.
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Relativistic and Theoretical Astrophysics

Introduction Gravitational lenses are a powerful tool for Astrophysics and Cosmology. The goals of this project are: i) to obtain a robust determination of the Hubble constant from the time delay measured between the images of a lensed quasar; ii) to study the individual and statistical properties of dark matter condensations in lens galaxies from

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