Abstract: Reconstructions of the 3D density and peculiar velocity fields from the distribution of observable galaxies provide a valuable probe of cosmic structure formation that is complementary to the study of density or velocity correlation functions. However, there is in fact a whole ensemble of possible reconstructions compatible with the noisy observations. In this talk I present CORAS, a new publicly available algorithm for the fast generation of such COnstrained Realizations from All-sky Surveys. This is achieved by combining a conservative Wiener filter estimator with random log-normal field realizations. I show the resulting reconstructions obtained from the 2MASS Redshift Survey (2MRS), and compare them with the observed peculiar galaxy velocities in the Cosmicflows-3 catalog to constrain the cosmic growth rate as well as the local bulk flow. I furthermore explain how the reconstructed velocities can be used to reduce both statistical and systematic errors on local measurements of the Hubble constant.
Title: Cosmology with Reconstructions of the Local Universe