The supergalactic plane redshift survey - A candidate for the great attractor

Redshift measurements, nearly 600 of which are new, are compiled for about 900 galaxies in a survey toward the apex of the large-scale streaming flow for ellipticals. The velocity histogram shows that the excess in galaxy number counts in this area is due to a substantial concentration of galaxies with discrete peaks at V about 3000 km/s and V about 4500 km/s. The centroid of the distribution, nicknamed the great attractor, is found to be at V about 4000 km/s, in good agreement with a model by Lynden-Bell et al. (1988) of a gravitational origin for the peculiar velocity field of elliptical galaxies. The amplitude of the overdensity can also be compared to that predicted by the dynamical model, although such a comparison is preliminary because the average density of the local universe on the appropriate scale is uncertain due to incomplete sampling. With the available calibration, the amplitude of the great attractor agrees well with the model. Low values of the cosmological density parameter Omega of about 0.1-0.2 are derived (assuming light traces mass), but the ability of simple spherical models to give reliable estimates of Omega is questioned. 28 references.