Cosmological Implications of Large-Scale Flows

Abstract

Cosmological implications of the observed large-scale peculiar velocities are reviewed, alone or combined with redshift surveys and CMB data. The latest version of the POTENT method for reconstructing the underlying three-dimensional velocity and mass-density fields is described. The initial fluctuations and the nature of the dark matter are addressed via statistics such as bulk flow and mass power spectrum. The focus is on constraining the mass density parameter $\Omega$, directly or via the parameter $\beta$ which involves the unknown relation between galaxies and mass. The acceptable range for $\Omega$ is found to be $0.4-1.0$. The range of $\beta$ estimates is likely to reflect non-trivial features in the galaxy biasing scheme, such as scale dependence. Similar constraints on $\Omega$ and $\Lambda$ from global measures are summarized.