LARGE-SCALE STREAMING MOTIONS IN THE LOCAL UNIVERSE

We have now measured the I-band luminosities and rotational velocities of 2400 southern spiral galaxies. This is a large, uniform, and unique data set with which to measure in detail the streaming motions found in the direction of the Great Attractor. Strong selection biases exist in the data, so a large region of sky at large angles to the flow has been used as a control. The galaxies in this control zone have been used to construct a table which gives their I luminosity as a function of rotational velocity and redshift. As the luminosity distribution of the galaxies in the control zone is similar to that in the Great Attractor region, this table has been used to measure V(pec) of the galaxies in the Great Attractor direction relative to galaxies in the control zone which is assumed to be a region of quiet Hubble flow. The accuracy of measurement of distance to a galaxy is 22%, provided its rotational velocity is greater than 63 km s-1. The fact that we are only concerned about large-scale motions allows averaging and increases the accuracy of measurement of V(pec) so that flows of 300 km s-1 or more would be detectable with the present sample out to distances of about 11,000 km s-1. The flow is not uniform over the Great Attractor region. It seems to be associated with the denser regions which participate in the flow of amplitude about 400 km s-1. In the less dense regions, the flow is small or non-existent. This makes the flow quite asymmetric and inconsistent with that expected from large-scale, parallel streaming flow that includes all galaxies out to 6000 km s-1 as previously thought. The flow cannot be modeled by a Great Attractor at 4300 km s-1 or the Centaurus clusters at 3500 km s-1. Indeed, from the density maps derived from the redshift surveys of ''optical'' and IRAS galaxies, it is difficult to see how the mass concentrations can be responsible particularly as they themselves participate in the flow. These results bring into question the generally accepted reason for the peculiar velocities of galaxies that they arise solely as a consequence of infall into the dense regions of the universe. To the north of the Great Attractor region, the flow increases and shows no sign of diminishing out to the redshift limit of 8000 km s-1 in this direction. We may have detected flow in the nearest section of the Great Wall.