A Re-Examination of the Origins of the Peculiar Velocity Field Within the Local Supercluster

Abstract

The recent re-evaulation of the peculiar velocity field outside the Local Supercluster (Dekel et al. 1999, ApJ 522) has permitted a re-examination of the origins of the peculiar velocity field within the Local Supercluster using the Mark III Catalog of Galaxy Peculiar Velocities for spiral galaxies. It is shown that the large-scale coherent pattern of peculiar velocities within the LSC are well-fit by a combination of the Outside-Region-(generated)-Motions (O-R-M) from the Potent model with a Virgocentric infall pattern that produces 220 km/s of Virgocentric infall at the Local Group (LG) towards the Virgo cluster moving at 88 km/s towards the LG. The part of the Cosmic Microwave Background motion of the LG this model cannot fit is that perpendicular to the Supergalactic plane (the SGZ direction). On what size scale the remaing 270 km/s CMB SGZ motion of the LG is shared by neighboring galaxies cannot be determined from the present data set, but may be found if we can accurately measure galaxy distances close to the Galactic plane.