Observational tests of the relation in hierarchical clustering models

¹ National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China
² Department of Astronomy, Beijing Normal University, Beijing 100875, PR China

Corresponding author: L.-M. Cheng, clm@class2.bao.ac.cn

Received: 22 February 2001
Accepted: 2 April 2001

Abstract

Observational determinations of the correlation between the characteristic density and the virial mass M_vir of dark halos constitute a critical test for models of hierarchical structure formation. Using the dynamical properties of dark halos reconstructed from the galaxy distributions in massive systems (groups/clusters) and the rotation curves in less massive systems (dwarf, low surface brightness and spiral galaxies) drawn from the literature, we confirm the existence of the -M_vir relation over a broad mass range from to , which is in gross consistency with the prediction of a flat cosmological model with and . It is pointed out that previous analyses based on the measurements of X-ray emitting gas and the hydrostatic equilibrium hypothesis, which claimed a shallower scale-free spectrum of for initial density fluctuations, may suffer from nongravitational heating influence especially in low-mass systems.