The Shape, Multiplicity, and Evolution of Superclusters in ΛCDM Cosmology

We determine the shape, multiplicity, size, and radial structure of superclusters in the ΛCDM concordance cosmology from z = 0 to z = 2. Superclusters are defined as clusters of clusters in our large-scale cosmological simulation. We find that superclusters are triaxial in shape; many have flattened since early times to become nearly two-dimensional structures at present, with a small fraction of filamentary systems. The size and multiplicity functions are presented at different redshifts. Supercluster sizes extend to scales of ∼ 100 − 200hMpc. The supercluster multiplicity (richness) increases linearly with supercluster size. The density profile in superclusters is approximately isothermal (∼ R) and steepens on larger scales. These results can be used as a new test of the current cosmology when compared with upcoming observations of large-scale surveys. Subject headings: large-scale structure of universe — cosmology: theory — galaxies: clusters: general Princeton University Observatory, Princeton, NJ 08544, USA Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA