Comparison of the SFI peculiar velocities with the IRAS 1.2-Jy gravity field

We present a comparison between the peculiar velocity fields measured from a recently completed I-band Tully-Fisher survey of field spirals (SFI) and that derived from the IRAS 1.2-Jy redshift survey galaxy distribution. The analysis is based on the expansion of these data in redshift space using smooth orthonormal functions, and is performed using low- and high resolution expansions, with an effective smoothing scale which increases almost linearly with redshift, The effective smoothing scales at 3000 km s(-1) are 1500 and 1000 km s(-1) for the low and high-resolution filters. The agreement between the high- and low-resolution SFI velocity maps is excellent. The general features in the filtered SFI and IRAS velocity fields agree remarkably well within 6000 km s(-1). This good agreement between the fields allows us to determine the parameter beta = Omega(0.6)/b, where Omega is the cosmological density parameter, and b is the linear biasing factor. From a likelihood analysis on the SFI and IRAS modes we find that beta = 0.6 +/- 0.1, independently of the resolution of the modal expansion. For this value of beta, the residual fields for the two filters show no systematic variations within 6000 km s(-1). Most remarkable is the lack of any coherent, redshift-dependent dipole flow in the residual field.