Abundances and correlations of structures beyond galaxy clusters.
XU W., FANG L.-Z. and DENG Z.
Abstract (from CDS):
We investigated the structures on scales beyond the typical clusters of galaxies. These structures are crucial to understanding the cosmic gravitational clustering in the previrialized stage, or quasi-linear regime. Based on the multiresolution analysis of the discrete wavelet transformation, we obtained statistically available ensembles of rcl clusters, i.e., the structures on scale rcl, in the range of 1≤rcl≤24 h–1 Mpc for both N-body simulation and the IRAS 1.2 Jy galaxy survey samples. When the mass-to-light ratio (M/L) on scales larger than that of the clusters asymptotically reaches a constant, we found that the abundances and correlations of these IRASrcl clusters were basically consistent with the predictions of the flat low-density CDM model (LCDM) and the open CDM model (OCDM), except that the model-predicted abundance of rcl=24 h–1 Mpc clusters seems to be higher than that predicted by the IRAS data. The standard CDM (SCDM) gives too much power and provides correlations that are too weak on all the scales. For a given rcl, the amplitude of the two-point correlation function ofrcl clusters increases with their richness. However, for a given richness (defined by the mean separation of neighboring objects), the clustering strengths of both the simulation and observation samples decline withrcl whenrcl is larger than 3-4 h–1 Mpc. Therefore, the ``universal'' increase of the correlation amplitude with the scale of objects from galaxies, groups, to poor, rich clusters is broken down for structures of rcl>3-4 h–1 Mpc. Superclusters should not be members of the ``universal'' increase family.
Cosmology: Theory - Galaxies: Clusters: General - Cosmology: Large-Scale Structure of Universe