A New Einstein Cross: a Highly Magnified, Intrinsically Faint Lyman-alpha Emitter at Z = 2.7

We report the discovery of a new Einstein cross at redshift zS = 2.701 based on Lyα emission in a cruciform configuration around an SDSS luminous red galaxy (zL = 0.331). The system was targeted as a possible lens based on an anomalous emission line in the SDSS spectrum. Imaging and spectroscopy from the W.M. Keck Observatory confirm the lensing nature of this system. This is one of the widest-separation galaxy-scale lenses known, with an Einstein radius θE ≃ 1.84 arcsec. We present simple gravitational lens models for the system and compute the intrinsic properties of the lensed galaxy. The total mass of the lensing galaxy within the 8.8 ± 0.1 kpc enclosed by the lensed images is (5.2 ± 0.1) × 10M⊙. The lensed galaxy is a low mass galaxy (0.2L∗) with a high equivalent-width Lyα line (EW rest Lyα = 46 ± 5 Å). Follow-up studies of this lens system can probe the mass structure of the lensing galaxy, and can provide a unique view of an intrinsically faint, high-redshift, star-forming galaxy at high signal-to-noise ratio. Subject headings: gravitational lensing — galaxies: elliptical, starburst, high-redshift — techniques: spectroscopic — galaxies: individual (SDSS J101129.49+014323.3)