PI: Kurtis A. Williams, University of Arizona, email@example.com
Address: Steward Observatory, 933 N Cherry Ave, Tucson, AZ 85721, USA
CoI: Ann I. Zabludoff, Univ. of Arizona
CoI: Charles Keeton, Rutgers University
CoI: Ivelina Momcheva, Univ. of Arizona
Title: The Importance of Lens Galaxies
Abstract: The study of strong gravitational lenses offers constraints on the shape and clumpiness of galaxy dark matter halos, the Hubble constant, and the dark energy that are independent of other methods. Unfortunately, relatively little is known about the \it environments of most lenses, whether at the lens redshift or along the line-of-sight, leading to significant biases in lens models. With Steward and NOAO facilities, we have been conducting a photometric and spectroscopic survey of lens environments that is yielding exciting results: more than ~80% of lenses lie in groups or clusters of galaxies, lenses in such dense environments are more likely to be quad lenses, and at least 10-50% of lenses have massive structures superposed along the line-of- sight that bias the constraints derived from lens models to a degree larger than the published errors. As a result, it has become clear that environment and line-of-sight effects must be considered. (And that such consideration may resolve the controversy over the abnormally high ratio of quad to double lenses.) \it This survey is delivering on its promises to the NOAO TAC. Here we propose to complete finally the photometric portion of this project by finishing our observations of the last of 76 lens fields.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360