The transformation of cluster galaxies at intermediate redshift

We combine imaging data from the Advanced Camera for Surveys ( ACS) with VLT/ FORS optical spectroscopy to study the properties of star- forming galaxies in the z = 0: 837 cluster Cl 0152 - 1357. We have morphological information for 24 star- forming cluster galaxies, which range in morphology from late- type and irregular to compact early- type galaxies. We find that while most star- forming galaxies have r(625) - i(775) colors bluer than 1.0, eight are in the red cluster sequence. Among the star- forming cluster population, we find five compact early- type galaxies that have properties consistent with their identification as progenitors of dwarf elliptical galaxies. The spatial distribution of the star- forming cluster members is nonuniform. We find none within R similar to 500 Mpc of the cluster center, which is highly suggestive of an intracluster medium interaction. We derive star formation rates from [ O II] lambda 3727 line fluxes and use these to compare the global star formation rate of Cl 0152 - 1357 to other clusters at low and intermediate redshifts. We find a tentative correlation between integrated star formation rates and T-X, in the sense that hotter clusters have lower integrated star formation rates. Additional data from clusters with low X- ray temperatures are needed to confirm this trend. We do not find a significant correlation with redshift, suggesting that evolution is either weak or absent between z = 0: 2 and 0.8.