Cosmological Parameters and Power Spectrum from Peculiar Velocities

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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 σ₈ Ωₘ⁰.⁶ = 0.8+/-0.2 at 90% confidence. Casting the results in the Ωₘ - ΩΛplane, yields complementary constraints to those of the high-redshift supernovae, together favoring a nearly flat, unbound and accelerating universe with comparable contributions from Ωₘ and ΩΛ. 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.