Comparison of the ENEAR Peculiar Velocities with the PSCz Gravity Field

Abstract

We present a comparison between the peculiar velocity field measured from the ENEAR all-sky $D_n-σ$ catalog and that derived from the galaxy distribution of the IRAS PSCz redshift survey. The analysis is based on a modal expansion of these data in redshift space by means of spherical harmonics and Bessel functions. The effective smoothing scale of the expansion is almost linear with redshift reaching 1500km/s at 3000km/s. The general flow patterns in the filtered ENEAR and PSCz velocity fields agree well within 6000km/s, assuming a linear biasing relation between the mass and the PSCz galaxies. The comparison allows us to determine the parameter $β=Ω^{0.6}/b$, where $Ω$ is the cosmological density parameter and $b$ is the linear biasing factor. A likelihood analysis of the ENEAR and PSCz modes yields $β=0.5 +- 0.1$, in good agreement with values obtained from Tully-Fisher surveys.