Where is the Information in Cluster Lensing?

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Dr Goldberg, Dr Richards and their team will develop and use a new technique to improve mass estimates for galaxy clusters that are derived from gravitational lensing -- the way that the light of distant galaxies is bent by gravity while passing by the cluster on its path to us. The new method combines the information from small distortions in the images of galaxies lying well away from the cluster on the sky (weak lensing) with the large distortions (strong lensing) seen when a galaxy lies almost directly behind a cluster. This combination is challenging because weak lensing typically demands that information is smoothed on angular scales large compared with the separation between the strong-lens images. Dr. Goldberg and his team will also refine their technique to include additional aspects of the measured galaxy images, including the banana-shape that weak lensing imposes on them. The technique will be applied to observations of binary clusters and merging systems.A woman graduate student and an undergraduate student will be trained as they participate in the research. Dr Goldberg has written a popular book on astronomy which he expects to be published in 2009, and Dr. Richards is director of the campus observatory. Both will continue their public outreach activities.