Discovery of a Double Source Plane Lens in the Hyper Suprime Cam Survey

Kenneth C. Wong

We report the discovery of a double source plane (DSP) lens in the Subaru Hyper Suprime Cam (HSC) survey. DSP lenses, which have two strongly lensed sources at distinct redshifts, are unique probes of cosmology and galaxy structure. SDSS spectroscopy reveals the main lens galaxy to be a massive early-type galaxy at z=0.795 with an estimated stellar mass of 8x10^11 M-sun. Using Magellan/FIRE spectroscopy, we confirm the redshifts of the two sources. The first source, S1, is a z=1.3 galaxy being lensed into a large arc and a smaller counterimage close to the lens center. The more distant source, S2, is a bluer z=1.99 galaxy with bright central emission that is being lensed by both the main lens galaxy and S1 into a complete Einstein ring. One of the images of the central region of S2 is further split into two images, suggesting the possibility of substructure or a line-of-sight perturber. Preliminary mass models of this system based on the HSC data place constraints on the physical properties of the lens, S1, and the possible substructure clump. Higher resolution imaging will improve our understanding of this complex system.