The Dynamical State of the Local Volume

The kinematics of galaxies with 10 megaparsecs (10 Mpc) of the Milky Way are investigated using published distances and radial velocities. With respect to the average Hubble flow (isotropic or simple anisotropic), there is NO systematic relation between peculiar velocity dispersion and absolute magnitude over a range of at least 12 magnitudes; neither is there any apparent variation with galaxy type or between field and cluster members. It appears that either there is no relationship between light and mass on these scales, or the peculiar velocities are not produced by gravitational interaction. There does appear to be a tendency toward greater dynamical relaxation within the Supergalactic Plane; however, the lack of data away from the Plane prevents any very firm conclusions. The extremely cold local flow of 40-60 km/s dispersion reported by some authors is shown to be an artifact of sparse data, a velocity dispersion of over 100 km/s being closer to the actual value. Galaxies with a high (positive) radial velocity have clearly been selected against, biasing the numerical results for local calculations. There are indications that the data set at hand does not sample the underlying dynamics well