The Peculiar Velocity Field in the Local Supercluster

A general method of estimating the peculiar velocity field expected, under the gravitational instability picture, around the outer parts of a mass concentration like a cluster of galaxies is derived and applied to a preliminary analysis of the Sandage-Tammann data on the distances and redshifts of nearby spiral galaxies. It is shown that there is evidence of a small peculiar velocity field of the sort expected. The field, if real, is consistent with a cosmologically flat universe, = 1; equally well, with a low-density cosmological model, 0.1. It is concluded that the data on the local peculiar velocity field do not yet offer a strong constraint on the density parameter . Subject headings: cosmology - galaxies: clusters of