The MX Northern Abell Cluster Redshift Survey

Abstract

The results from the COBE satellite show the existence of structure on scales ~10% or more of the horizon scale of the universe. Rich clusters of galaxies from the Abell/Abell, Corwin, & Olowin catalogs show evidence of structure on scales of 100 h-1 Mpc and hold the promise of confirming structure on the scale of the COBE results. An impediment to that promise has been that redshift information has been unavailable for a large percentage of these clusters, so knowledge of their three-dimensional distribution has had large uncertainties. We have been working to greatly expand the sample of Abell clusters with reliable redshifts. Our approach in this effort, through the MX Northern Abell Cluster Redshift Survey, has been to measure redshifts of at least 25 galaxies in each of 95 R ? 1 Abell cluster fields with m10 ? 16.8 and zero or one previously measured redshift. Of these 95 observed Abell clusters, 88 new cluster redshifts were obtained with an average of nine cluster member galaxy redshifts per field. Two clusters were found to be chance projections of galaxies along the line of sight, while five cluster observations did not provide enough galaxy redshifts to make a positive identification. This work has resulted in a deeper, 98% complete, and more reliable sample of three-dimensional positions of rich Abell clusters in the northern hemisphere. The primary intent of this survey has been to produce a larger and more complete sample of rich Abell clusters that can be used as tracers for large-scale structure. Through analyses with tools such as the two-point correlation function, power spectrum, and velocity dispersions, this sample can be used to constrain theoretical models better for the formation of structure we see in the universe today.