THE LARGEST VIRIALIZED DARK HALO IN THE UNIVERSE

Abstract

Using semi-analytic approach, we present an estimate of the properties of the largest virialized dark halos in the present universe for three different scenarios of structure formation: SCDM, ΛCDM and OCDM models. The resulting virial mass and temperature increase from the lowest values of 1.6 × 1015 h-1 M⊙ and 9.8 keV in OCDM, the mid-range values of 9.0 × 1015 h-1 M⊙ and 31 keV in ΛCDM, to the highest values of 20.9 × 1015h-1M⊙, 65 keV in SCDM. As compared with the largest virialized object seen in the universe, the richest clusters of galaxies, we can safely rule out the OCDM model. In addition, the SCDM model is very unlikely because of the unreasonably high virial mass and temperature. Our computation favors the prevailing ΛCDM model in which superclusters may be marginally regarded as dynamically-virialized systems.