1996/02/01 by Somak Raychaudhury, William C. Saslaw · 1 citation
Computer Science · Physics and Astronomy · #Galaxies: Formation, Evolution, Phenomena #Gaussian Processes and Bayesian Inference #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.1086/177078
published as Astrophys.J. 461 (1996) 514 · 28 pages, gzipped postscript file, including 11 figures and 2 tables; To appear in the Astrophysical Journal, March 1996
arxiv created 1996/02/01 · openalex publication_date 1996/04/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We give the first determination of the observed peculiar velocity distribution function for a representative sample of galaxies which includes a wide range of clustering properties. We explore in detail the effects of uncertainties in sampling and in distance measures on the estimated distribution function. The observed distribution function is consistent with an earlier prediction of gravitational clustering, over the entire range of peculiar velocities, from field galaxies to rich clusters, on scales up to 50 h100_-1^ Mpc. In the simplest consistent model, most of the inhomogeneous mass of the universe is in galaxies or their halos. We estimate the "Mach number" for the bulk flow within 50 h100_-1^ Mpc from us to be M = DELTAνr_/<νr_2^>1/2^ = 599/717 ~ 0.8, which includes the effect of high-dispersion galaxies in clusters. The observed velocity distribution function agrees quantitatively with N-body simulations with OMEGA0_ = 1 that have galaxies with a realistic mass spectrum. Further comparisons of the observed distribution with N-body simulations will provide a new technique for measuring H0_ and OMEGA0_. These results provide new tests for all models of galaxy clustering.