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Cold dark matter. 2: Spatial and velocity statisticsWe examine high-resolution gravitational N-body simulations of the omega = 1 cold dark matter (CDM) model in order to determine whether there is any normalization of the initial density fluctuation spectrum that yields acceptable results for galaxy clustering and velocities. Dense dark matter halos in the evolved mass distribution are identified with luminous galaxies; the most massive halos are also considered as sites for galaxy groups, with a range of possibilities explored for the group mass-to-light ratios. We verify the earlier conclusions of White et al. (1987) for the low-amplitude (high-bias) CDM model-the galaxy correlation function is marginally acceptable but that there are too many galaxies. We also show that the peak biasing method does not accurately reproduce the results obtained using dense halos identified in the simulations themselves. The Cosmic Background Explorer (COBE) anisotropy implies a higher normalization, resulting in problems with excessive pairwise galaxy velocity dispersion unless a strong velocity bias is present. Although we confirm the strong velocity bias of halos reported by Couchman & Carlberg (1992), we show that the galaxy motions are still too large on small scales. We find no amplitude for which the CDM model can reconcile simultaneously and galaxy correlation function, the low pairwise velocity dispersion, and the richness distribution of groups and clusters. With the normalization implied by COBE, the CDM spectrum has too much power on small scales if omega = 1.
Document ID
19950037383
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Gelb, James M. (MIT, Cambridge, MA United States)
Bertschinger, Edmund (MIT, Cambridge, MA United States)
Date Acquired
August 16, 2013
Publication Date
December 1, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 436
Issue: 2
ISSN: 0004-637X
Subject Category
ASTROPHYSICS
Funding Number(s)
CONTRACT_GRANT: NSF AST-90-01762
CONTRACT_GRANT: NAGW-2381
Distribution Limits
Public
Copyright
Other