Wiener Reconstruction of the IRAS 1.2Jy Galaxy Redshift Survey: Cosmographical Implications

Abstract

We utilise the method of Wiener reconstruction with spherical harmonics and Bessel functions to recover the density and velocity fields from the IRAS 1.2Jy redshift survey. The results are robust to changes in prior parameters and the number of expansion coefficients. Maps of these fields are presented in a variety of projections. Many known structures are observed, including clear confirmations of the clusters N1600 and A3627. The Perseus-Pisces supercluster appears to extend out to roughly 9000km/s, and the reconstruction shows `backside infall' to the Centaurus/Great Attractor region. A qualitative comparison of the reconstructed IRAS gravity field with that from Tully-Fisher peculiar velocity measurements (Mark III) shows reasonable agreement. The Wiener reconstruction of the density field is also the optimal reconstruction (in the minimum variance sense) of any quantity which is linear in the density contrast. We show reconstructions of three such quantities. The misalignment angle between the IRAS and CMB Local Group dipoles is only 13 degrees out to 5000km/s, but increases to 25 degrees out to 20,000km/s. The reconstructed IRAS bulk flow out to 5000km/s is roughly 300km/s, which agrees in amplitude with that derived from the Mark III peculiar velocities (370km/s). However, the two bulk flow vectors deviate by 70 degrees. Finally, moment of inertia analysis shows that the Wiener reconstructed Supergalactic Plane is aligned within 30 degrees of that defined by de Vaucouleurs.