AAS 203rd Meeting, January 2004
Session 30 Galaxy Clusters and Large Scale Structure I
Oral, Monday, January 5, 2004, 2:00-3:30pm, Centennial I/II

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[30.03] The Evolving Galaxy Population of Cluster Cl0024+1654 at z=0.4

A. J. Metevier (UC Santa Cruz), D. C. Koo (UCO/Lick Observatory)

We present the results of an effort to pinpoint evolutionary signatures in members of cluster Cl0024+1654 at z=0.4 through an investigation of their spectral properties, structures, and kinematics. Our study employs measurements from deep Keck spectroscopy and extensive imaging from the Hubble Space Telescope archive. We find that Cl0024 has a complicated structure which is likely affecting the cluster's constituent galaxy population. We reconfirm Butcher & Oemler's finding of a high fraction of blue galaxies (~ 20%) in the cluster. We also measure a large proportion (~ 50%) of disk-dominated emission-line members. We focus on the structures of Cl0024 S0s and blue galaxies for observational clues about their ongoing evolution. We find no evidence for rapid evolution of cluster S0s from analysis of their colors and color gradients. However, blue Cl0024 members appear somewhat redder and have smoother light profiles than blue field galaxies at z=0.4, suggesting that the high-density cluster environment may suppress star formation in spirals. Lastly, we measure the rotation velocities of 15 cluster spirals in a Tully-Fisher study. We find evidence for ~ 0.7 mag luminosity brightening in Cl0024 spirals as compared to local field and cluster samples. The most overluminous Cl0024 members appear to be the most small, blue, and slowly rotating galaxies in our sample -- likely progenitors of present-day cluster dwarfs.

The author(s) of this abstract have provided an email address for comments about the abstract: anne@ucolick.org

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.