* Astronomy

Title: SDSS J094604.90+183541.8: A Gravitationally Lensed Quasar at z=4.8
Authors: Ian D. McGreer (1), Patrick B. Hall (2), Xiaohui Fan (1), Fuyan Bian (1), Naohisa Inada (3), Masamune Oguri (4), Michael A. Strauss (5), Donald P. Schneider (6), Kara Farnsworth (1) ((1)Steward Observatory, (2)York University, (3) Cosmic Radiation Laboratory, (4) National Astronomical Observatory of Japan, (5)Princeton University Observatory, (6)Pennsylvania State University)

We report the discovery of a gravitationally lensed quasar identified serendipitously in the Sloan Digital Sky Survey (SDSS). The object, SDSS J094604.90+183541.8, was initially targeted for spectroscopy as a luminous red galaxy, but the SDSS spectrum has the features of both a z=0.388 galaxy and a z=4.8 quasar. We have obtained additional imaging that resolves the system into two quasar images separated by 3.06 arcsec and a bright galaxy that is strongly blended with one of the quasar images. We confirm spectroscopically that the two quasar images represent a single lensed source at z=4.8 with a total magnification of 3.2, and we derive a model for the lensing galaxy. This is the highest redshift lensed quasar currently known. We examine the issues surrounding the selection of such an unusual object from existing data and briefly discuss implications for lensed quasar surveys.

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