AAS 199th meeting, Washington, DC, January 2002
Session 100. Galaxy Clusters and Mergers
Display, Wednesday, January 9, 2002, 9:20am-6:30pm, Exhibit Hall

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[100.05] Using the Bull's Eye Effect to Probe \Omegam

B. C. Thomas, A. Melott, H. Feldman (University of Kansas)

Maps of galaxy position in redshift space are distorted relative to the true galaxy positions due to peculiar velocities. Two types of distortion are apparent: 1) Stretching ("Fingers of God") due to random pecuilar motion. 2) Compression due to coherent motion from gravitational infall. These two together lead to the "Bull's Eye" effect. The strength of the distortions depends on \Omegam and traces both the visible and dark components.

We characterize the effect by looking at a slice of a density field (from simulations) and measuring the distance between contour crossings in radial and transverse directions. Comparing distances in the two directions yeilds a measure of the strength of the effect and hence \Omegam.

This work is supported by the NSF (Grant AST-0070702) and the Madison and Lila Self Graduate Fellowship.

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