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N. Rahman, S. F. Shandarin (Dept. of Physics and Astronomy, U. Kansas)
Cluster abundance test puts stringent constraints on the models of the structure formation. This test can constrain cosmological parameters such as matter density (\Omega0 = \Omegab + \Omegacdm + \Omegahdm) in the Universe and the amplitude of the mass density fluctuations (\sigma8). We present a comparison between two observational and three theoretical mass functions for eight cosmological best-fit models suggested by the data from recently the completed BOOMERANG-98, MAXIMA-1 cosmic microwave background (CMB) anisotropy experiments as well as peculiar velocities (PVs) and type Ia supernovae (SN) observations. We notice that models are in general show disagreement with the abundances of X-ray clusters at ~1014.7 h-1M\odot. On the hand, we notice that several models such as, the BOOM+MAX+COBE:I, Refined Concordance and \LambdaMDM are in a good agreement with the abundances of optical clusters. The P11 and especially Concordance models predict a slightly lower abundances than observed at ~1014.6 h-1M\odot. The BOOM+MAX+COBE:II and PV+CMB+SN models predict a slightly higher abundances than observed at ~1014.9 h-1M\odot. The nonflat MAXIMA-1 is in a fatal conflict with the observational cluster abundances and can be safely ruled out. Our analysis justifies the present notion of the low matter density (\Omega0 ~ 0.40 ) Universe dominated by the some unknown dark energy density (\Omega\Lambda ~0.60).
The author(s) of this abstract have provided an email address for comments about the abstract: nurur@kusmos.phsx.ukans.edu