The HST/ACS Coma Cluster Treasury Survey: The Nature of Dwarf Galaxies Deep in the Heart of Coma

The HST/ACS Coma Cluster Treasury Survey addresses many outstanding issues concerning galaxy formation, and provides a fundamental low-redshift reference, and comparison dataset for cluster studies at high redshift. We present preliminary results from our follow-up Keck/DEIMOS spectroscopic survey, which targets galaxies in the dense cluster core. Accurate velocity dispersions for 41 cluster dwarf galaxies were measured. These were selected from CFHT and HST/ACS images. Combined with accurate structural information, velocity dispersions facilitate a detailed analysis of the fundamental galaxy “scaling laws” for cluster dwarf galaxies. We investigate the behaviour of velocity dispersion with metallicity, by measuring absorption line indices for the 15 brightest cluster dwarfs. These observations help constrain galaxy formation models and provide further insight into the formation and evolution of dwarf galaxies in dense environments.