Predicting the peculiar velocities of nearby galaxies

We use the Least Action Principle to predict the peculiar velocities of PSC-z galaxies inside cz = 2000kms(-1). Linear theory is used to account for tidal effects to cz = 15000kms(-1), and we iterate galaxy positions to account for redshift distortions. As the Least Action Principle is valid beyond Linear theory, we can predict reliable velocities even for very nearby galaxies (ie ie less than or equal to 500kms(-1)). These predicted peculiar velocities are then compared with the observed velocities of 12 galaxies with Cepheid distances. The combination of the PSC-z galaxy survey (with its large sky coverage and uniform selection), with the accurate Cepheid distances, makes this comparison relatively free from systematic effects. We find that galaxies are good tracers of the mass, even at small (less than or equal to 10h(-1) Mpc) scales; and under the assumption of no biasing, beta less than or equal to 0.75 (at 90% confidence). We use the reliable predicted peculiar velocities to estimate Ho from the local volume without "stepping up" the distance ladder, finding a confidence range of 65 - 75kms(-1)Mpc(-1) (at 90% confidence).