1994/04/08 by Neta A. Bahcall, M. Gramann, Bahcall, Neta A. +4
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9404020
25p plaintex submitted to The Astrophysical Journal
arxiv created 1994/04/08 · openalex publication_date 1994/04/08 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The distributions of peculiar velocities of rich clusters and of groups of galaxies are investigated for different cosmological models and are compared with observations. Four cosmological models are studied: standard (Ω=1) CDM, low-density CDM, HDM (Ω=1), and PBI. We find that rich clusters of galaxies exhibit a Maxwellian distribution of peculiar velocities in all models, as expected from a Gaussian initial density fluctuation field. The cluster 3-D velocity distribution is generally similar in the models: it peaks at v ∼ 500 km s-1, and extends to high cluster velocities of v ∼ 1500 km s-1. Approximately 10% of all model rich clusters move with high peculiar velocities of v ≥ 103 km s-1. The highest velocity clusters frequently originate in dense superclusters. The group velocity distribution is, in general, similar to the velocity distribution of the rich clusters. In all but the low-density CDM model, the mass exhibits a longer tail of high velocities than do the clusters. This high-velocity tail originates mostly from the high velocities that exist within rich clusters. The model velocity distributions of groups and clusters of galaxies are compared with observations. The data are generally consistent with the models, but exhibit a somewhat larger high-velocity tail, to vr ∼ 3000 km s-1. While this high-velocity tail is similar to the HDM model predictions, the data are consistent with the other models studied, including the low-density CDM model, which best fits most other large-scale structure observations. The observed velocity