NEARBY GALAXY FLOWS MODELED BY THE LIGHT-DISTRIBUTION

The observed distribution of light in the Local Supercluster has been used to determine the expected velocities of galaxies if the assumptions are valid that nonexpansion motions are generated by gravitational perturbations and that mass is distributed like the light. Since detailed knowledge of the light distribution extends to only 3000 km s-1, three extra sources are added at large distances: one associated with the Great Attractor, one loosely with the Perseus-Pisces Supercluster region, and one with the Shapley Concentration at a distance corresponding to 13,800 km s-1. The nearer two sources are motivated by improvements they offer to chi-2 fits while the distant source is required to get agreement with the cosmic microwave background dipole. Comparison is made with observed velocity field maps based on 301 high-quality distance estimates in 142 groups and 53 individual galaxies. The assumption that gravitational perturbations must dominate the generation of peculiar velocities is substantiated and M/L congruent-to 144h-OMEGA-0(0.4) is found. A surprisingly strong conclusion can be drawn that the clumped mass is clustered on scales of less than 1 Mpc with M/L approximately 100 and that an insignificant amount of additional mass is clustered on scales between 1 Mpc and approximately 20 Mpc. A value of OMEGA(gal) approximately 0.03-0.1 is associated with clumped mass. The location of the three sources beyond 3000 km s-1 involves some speculation, but a curious influence of these long-range forces is a slowing of the merger of the nearest groups. There are hints of velocity streaming with coherence over 20,000 km s-1 and mass fluctuations on 10(17) M. scales. The model provides a natural description of the "local velocity anomaly." The chi-2 fit for the preferred model results in an equivalent rms uncertainty in the differences between observed and model velocities of 18% of the observed velocity.