2005ApJ...625L.103S

We have discovered strong gravitational lensing by the galaxy ESO 325-G004, in images obtained with the Advanced Camera for Surveys on the Hubble Space Telescope. The lens galaxy is a boxy group-dominant elliptical at z=0.0345, making this the closest known galaxy-scale lensing system. The lensed object is very blue (B-I_C~1.1), and forms two prominent arcs and a less extended third image. The Einstein radius is R_Ein=1.9 kpc (∼3" on the sky), much smaller than the lens galaxy effective radius of 8.5 kpc. Assuming a high redshift for the source, the mass within R_Einis 1.4x10¹¹ M_☉, and the mass-to-light ratio is 1.8 (M/L)_☉,I. The equivalent velocity dispersion is σ_lens=310 km/s, in excellent agreement with the measured stellar dispersion σ_v=320 km/s. Modeling the lensing potential with a singular isothermal ellipse (SIE), we find close agreement with the light distribution. The best-fit SIE model reproduces the ellipticity of the lens galaxy to ∼10%, and its position angle within 1°. The model predicts the broad features of the arc geometry as observed; the unlensed magnitude of the source is estimated at I_C∼23.75. We suggest that ∼60 similarly massive elliptical galaxies within z<0.1 will exhibit such a luminous, multiply imaged source.