Bulk Motions of Spiral Galaxies in the z = 0.03 Volume

Abstract

We analyze the peculiar velocity field for 2400 flat spiral galaxies selected from an infrared sky survey (2MFGC). The distances to the galaxies have been determined from the Tully-Fisher relation in the photometric J band with a dispersion of 0.45 mag. The bulk motion of this sample relative to the cosmic microwave background (3K) frame has an amplitude of 199+/-37 km/s in the direction l = 290 +/- 11, b = +1 +/- 9 degree. The amplitude of the dipole motion tends to decrease with distance in accordance with the expected convergence of bulk flows in the 3K frame. We believe that external massive attractors similar to the Shapley cluster concentration are responsible for \~60% of the local flow velocity in the z = 0.03 volume.

15 pages, 6 figures