The Kinematic State of the Local Volume

The kinematics of galaxies with 10 megaparsecs (10 Mpc) of the Milky Way isinvestigated using published distances and radial velocities. With respect tothe average Hubble flow (isotropic or simple anisotropic), there is NOsystematic relation between peculiar velocity dispersion and absolute magnitudeover a range of 10 magnitudes; neither is there any apparent variation withgalaxy type or between field and cluster members. There are several possibleexplanations for the lack of variation, though all have difficulties: eitherthere is no relationship between light and mass on these scales, or thepeculiar velocities are not produced by gravitational interaction, or thebackground dynamical picture is wrong in some systematic way. The extremelycold local flow of 40-60 km/s dispersion reported by some authors is shown tobe an artifact of sparse data, a velocity dispersion of over 100 km/s beingcloser to the actual value. Galaxies with a high (positive) radial velocityhave been selected against in studies of this volume, biasing numericalresults.Comment: aastex preprint, 40 figures, accepted by ApJ. Miscalculation of absolute magnitudes corrected. No significant changes in conclusion