Star formation in low-redshift cluster dwarf galaxies.

The evolution of galaxies in dense environments can be affected by close encounters with neighbouring galaxies and interactions with the intracluster medium. Dwarf galaxies are important as their low mass makes them more susceptible to these effects than giant systems. Combined luminosity functions (LFs) in the r- and u-band of 15 galaxy clusters were constructed using archival data from the Canada-France-Hawaii Telescope. LFs were measured as a function of cluster-centric radius from stacked cluster data. Marginal evidence was found for an increase in the faint-end slope of the u-band LF relative to the r-band with increasing cluster-centric radius. The dwarf-to-giant ratio (DGR) was found to increase toward the cluster outskirts, with the u-band DGR increasing faster with cluster-centric radius compared to the r-band. The dwarf galaxy blue fraction was found to be a factor of ~2 times larger than the giant galaxy blue fraction over all measured cluster-centric distance (~5sigma level). The central concentration (C) was used as a proxy to distinguish nucleated versus non-nucleated dwarf galaxies. The ratio of high-C to low-C dwarf galaxies was found to be ~2 times greater in the inner cluster region compared to the cluster outskirts (2.8sigma level). The faint-end slope of the r- and u-band LF for the cluster outskirts (0.6 < r/r_200 < 1.0) is steeper than the SDSS field LF. Decrease in the faint-end slope of the r- and u-band cluster LFs towards the cluster centre is consistent with the quenching of star formation via ram pressure stripping and galaxy-galaxy interactions.