Cosmological Parameters and Power Spectrum from Peculiar Velocities

Abstract

The power spectrum of mass density fluctuations is evaluated from the Mark III and the SFI catalogs of peculiar velocities by a maximum likelihood analysis, using parametric models for the power spectrum and for the errors. The applications to the two different data sets, using generalized CDM models with and without COBE normalization, give consistent results. The general result is a relatively high amplitude of the power spectrum, with σ_8 Ω_m^{0.6} = 0.8+/-0.2 at 90% confidence. Casting the results in the Ω_m - Ω_Λplane, yields complementary constraints to those of the high-redshift supernovae, together favoring a nearly flat, unbound and accelerating universe with comparable contributions from Ω_m and Ω_Λ. Further implications on the cosmological parameters, arising from a joint analysis of the velocities together with small-scale CMB anisotropies and the high-redshift supernovae, are also briefly described.

8 pages, 3 figures. To appear in Proceedings of the Cosmic Flows Workshop, Victoria, B.C., Canada, July 1999, eds. S. Courteau, M. Strauss, and J. Willick