PECULIAR VELOCITIES AND GALAXY CLUSTERING - DO BULK AND SHELL MOTIONS HAVE THE SAME ORIGIN

We use recent estimations of the galaxy two-point correlation function xi(r) to perform new calculations of the rms peculiar velocities expected on different scales. The novelty of our approach consists in using the double power-law fit for 1 + xi(r) up to separations approximately 30 h-1 Mpc (H-0 = 100 h km s-1 Mpc-1), as determined by Guzzo et al. and by Calzetti, Giavalisco, & Meiksin, instead of the single power-law model up to about 10-15 h-1 Mpc usually adopted for xi(r). We find that the apparent contradiction existing between the peculiar motion of the Local Group relative to distant galaxies and the bulk motion determined by Dressler et al. can be resolved within this new approach and that the measured amplitudes of the peculiar velocities are in agreement with those expected from the average density fluctuations as described by the two-point correlation function. Implications of the new correlation function in the CDM cosmological scenario are also discussed.