Consistent beta values from density-density and velocity-velocity comparisons

Abstract

We apply a new algorithm, called the Unbiased Minimal Variance (hereafter UMV) estimator, to reconstruct the cosmic density and peculiar velocity fields in our local universe from the SEcat catalog of peculiar velocities comprising both early (ENEAR) and late type (SFI) galaxies. The reconstructed fields are compared with those predicted from the IRAS PSCz galaxy redshift survey to constrain the value of beta = Omega_m^{0.6}/b, where Omega_m and b are the mass density and the bias parameters. The comparison of the density and velocity fields is carried out within the same methodological framework, and leads, for the first time, to consistent values of beta, yielding beta = 0.57_{-0.13}^{+0.11} and beta = 0.51 +/- {0.06}, respectively. We find that the distribution of the density and velocity residuals, relative to their respective errors, is consistent with a Gaussian distribution with sigma approximately 1, indicating that the density field predicted from the PSCz is an acceptable fit to that deduced from the peculiar velocities of the SEcat galaxies.