* Astronomy

Title: SDSS J1640+1932: a spectacular galaxy-quasar strong lens system
Author: Lin Wang, Yiping Shu, Ran Li, Zheng Zheng, Zhonglue Wen, Guilin Liu

We present Canada-France-Hawaii Telescope (CFHT) MegaCam observations of a galaxy-quasar strong gravitational lens system, SDSS J1640+1932. This system, located at z=0.195 (foreground elliptical galaxy) and z=0.778 (background quasar), was first visually identified by us in the Sloan Digital Sky Survey (SDSS) database. Our CFHT imaging with an angular resolution of 0.7" clearly resolves 4 lensed images and a nearly complete Einstein ring. Modeling the system with a singular isothermal ellipsoid (SIE) total mass distribution, we find an Einstein radius of 2.49"_{-0.049}^{+0.063} enclosing a inferred mass of 7.25_{-0.29}^{+0.37} x 10^11 solar masses. The quasar and its host galaxy have been magnified by a factor of 23, and the time delay relative to the leading image is determined to be 23.4-25.2 days. These parameters vary minimally when our model is fitted to the {\it{g}}-, {\it{r}}- or {\it{i}}-band images.

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