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D. H. McIntosh (Steward Observatory), H.-W. Rix (MPIA), N. Caldwell (SAO/Whipple Observatory)
Do star-forming spirals accreted recently by massive clusters evolve in a few Gyrs. into smooth disk galaxies with little or no current star formation? Hierarchical models of large-scale structure and the observed effect of the cluster environment on galaxy morphologies and star formation rates have given rise to many theories predicting such cluster galaxy evolution. Depending on the star formation truncation mechanism timescale, the more recent cluster arrivals should still have relatively young stellar populations and thus bluer colors (esp. in U-V) than the older, red early-types (E/S0) that define the cluster color-magnitude relation. Yet to date no significant population of bluer S0's has been found in local clusters, though we note previous studies have concentrated on the inner regions (R<0.5Mpc) of nearby clusters, which are expected to be dominated by older members. Therefore, we have obtained wide-field (R>0.6/h Mpc) UVI imaging for 10 local (z<0.06) Abell clusters, with 100's of spectroscopically confirmed members, to search the cluster outskirts for bluer S0's which may be recently accreted spirals. From our detailed photometry, we have measured structural parameters for a sample of over 300 U-band selected, spectroscopically confirmed members, by fitting each galaxy surface brightness profile with a PSF-convolved, de Vaucouleur's bulge plus exponential disk model. We have found a population of blue, disk-dominated galaxies, that are predominately in the outskirts (>0.75/h Mpc projected radius) of our first analyzed cluster, Abell 754 at z=0.053. We present the photometric and structural properties of this blue population.
The author(s) of this abstract have provided an email address for comments about the abstract: dmac@slayer.as.arizona.edu