The Large Scale Distribution of Galaxies in the Shapley Supercluster

We present new results of our wide-field redshift survey of galaxies in a 182 square degree region of the Shapley Supercluster (SSC) based on observations with the FLAIRII spectrograph on the UK Schmidt Telescope (UKST). In this paper we present new measurements to give a total sample of redshifts for 710 bright (R ≤ 16.6) galaxies, of which 464 are members of the SSC (8000 < v < 18000kms ). Our data reveal that the main plane of the SSC (v ≈ 14500km s ) extends further than previously realised, filling the whole extent of our survey region of 10 degrees by 20 degrees on the sky (35 Mpc by 70 Mpc, H0 = 75kms −1 Mpc). There is also a significant structure associated with the slightly nearer Abell 3571 cluster complex (v ≈ 12000km s ) with a caustic structure evident out to a radius of 6 Mpc. These galaxies seem to link two previously identified sheets of galaxies and establish a connection with a third one at V= 15000kms near R.A. = 13h. They also tend to fill the gap of galaxies between the foreground HydraCentaurus region and the more distant SSC. We calculate galaxy overdensities of 5.0±0.1 over the 182 square degree region surveyed and 3.3 ± 0.1 in a 159 square degree region excluding rich clusters. Over the large region of our survey the inter-cluster galaxies make up 46 per cent of all galaxies in the SSC region and may contribute a similar amount of mass to the cluster galaxies.