NEW MEASUREMENTS OF DISTANCES TO SPIRALS IN THE GREAT ATTRACTOR - FURTHER CONFIRMATION OF THE LARGE-SCALE FLOW

Hα rotation curves and CCD photometry have been obtained for 117 Sb-Sc spiral galaxies in the direction of the large-scale streaming flow described in the period 1987-1990 by Dressier et al., Lynden-Bell et al., Dressler and Faber, and Burstein, Faber, and Dressier. By means of the Tully-Fisher relation, these data are used to predict distances to these galaxies and, by comparison with their observed radial velocities, their peculiar motions relative to a smooth Hubble flow. The new data confirm the results of these earlier studies of a coherent flow pattern in a large region called the "great attractor." For the first time, evidence is found for backside infall into the great attractor. Taken as a whole, the data sets for E, SO, and spiral galaxies support the model proposed by Lynden-Bell et al. of a large, extended overdensity centered at ∼45h-1 Mpc that perturbs the Hubble flow over a region ≲100h-1 Mpc in diameter. Observation of the full "s-wave" in the Hubble flow establishes this scale for the structure, providing a strong constraint for models of structure formation, like those based on hot or cold dark matter.