The Ophiuchus Cluster and a Large-Scale Structure toward the Galactic Centre

Abstract

The Ophiuchus Cluster is one of the most luminous X-ray clusters in the local Universe, and may be a key cluster for the local large-scale structure. Our preliminary redshift-survey with FLAIR and 6dF for the cluster shows the following: 1) a velocity dispersion of the Ophiuchus cluster is found to be 1050 ± 50 km s-1, which is consistent with its large X-ray luminosity, 2) the cluster accompanies several clusters and groups of galaxies within a distance of 8° from the cluster centre, implying that it is a large and massive enough to be classified as a supercluster, 3) from its closeness to the position of the Great Attractor in the sky, the Ophiuchus Supercluster may play some role in its gravitational potential, as may the Shapley Concentration, and 4) there is an extensive foreground void up to cz≈ 4000 km s-1 in the survey area, implying that it is a continuation of the Local Void.