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Session 6 - Evolution, Survey and Clusters of Galaxies.
Display session, Monday, June 10
We report here preliminary results from a study of radio galaxy evolution in a sample of very rich Abell clusters between 0.02\le z\le0.40. We have obtained deep VLA observations of 60 rich clusters, including 4 clusters at 0.4. Most have B and R wide-field CCD images. We are looking for evolution in rich cluster environments with changing epoch, and imaging out to 2.5 Mpc from the cluster centers to study any supercluster-associated phenomena. Initial results of a low-redshift high-richness sample between 0.10\le z\le0.18 shows that the probablity of a galaxy being a radio galaxy is less than a similar richness blue-populated cluster at a z=0.25. Spectroscopy of two low-redshift clusters have shown the galaxies to contain old stellar populations and not starburst galaxies. This results agrees with local rich clusters which display a lack of galaxies undergoing starburst. Preliminary work seems to indicate that distant blue-populated clusters display an enhancement in the number radio galaxies compared to current-epoch rich clusters.
Program listing for Monday