Dwarf Galaxies in Clusters with z < .02

We present initial results of a study of low surface brightness dwarf galaxies in six different Abell clusters (A3526,426,2634,1367,400,262) as part of our program to determine the luminosity functions, clustering properties, and morphologies of dwarfs in a wide range of cluster environments. The goal of this project is to obtain a complete sample of all rich z < .02 clusters which will complement the work done on other nearby clusters - namely Virgo and Fornax - and extend out to the recent work done on Coma. A thorough understanding of the faint-end of the luminosity function is important to establish whether dwarfs - in particular their dark matter (DM) halos - can plausibly account for much of the DM content of clusters. Also, because our CCD survey has the advantage of not only looking deep, but also covering large fractions of the total cluster area, these data are extremely useful for studying the effect of the environment on dwarfs. This is accomplished by examining dwarf morphology as a function of location, clustering properties as a function of luminosity and type, and global dwarf-to-galaxy ratios.

We have obtained deep V-band CCD images covering ~1 square degree in each cluster and reaching a limiting surface brightness of 26.5 mag/square degree at the Las Campanas 1m and Michigan-Dartmouth-MIT 1.3m telescopes. Control fields are used to statistically correct for background galaxy counts, and false galaxy analysis is being implemented to assess completeness and the selection effects inherent in detecting these low surface brightness galaxies. In addition, we shall present the results of fiber spectroscopy data which have been obtained for 550 galaxies in A3526 at the LCO 2.5m with the 2D-Frutti. Velocities have been determined to establish cluster membership and will also be used to study the dwarf kinematics.


kristin@astro.lsa.umich.edu