The Shapley Supercluster. II. Spectroscopic observations in a wide area and general morphology

Abstract

We report 2868 new multi-object spectroscopic measurements of galaxy redshifts in an area roughly 12°$\times$ 6°(right ascension $\times$ declination) centered on the Shapley Supercluster (SSC). These correspond to 2627 different galaxies. Including other measurements reported in the literature, the total number of galaxies with measured redshifts in a 19°$\times$ 16°area centered on the supercluster now reaches 5090. Of these, 2949 lie in the redshift range 9,000 - 18,000 km s$^{-1}$, which we tentatively identify with the SSC. This unprecedented sample allows a quite detailed qualitative morphological study of the SSC. Based on the three-dimensional distribution of galaxies and clusters of galaxies, we identify several sub-condensations of the supercluster, as well as walls and filaments connecting them. We also find another supercluster in the background, at redshift $\sim$ 23,000 km s$^{-1}$.