Dynamics of the Local Universe: cosmic velocity flows and voids

Abstract

A valuable amount of information is available in peculiar velocities of galaxies. Peculiar velocity surveys have recently allowed the discovery of potential problems with LCDM. Nonetheless, their direct observation through distance measurements remains a daunting task. Another way of considering the problem is to use orbit reconstruction methods assuming some mass-to-light assignment for galaxies. We give here two applications of this procedure for the study of large-scale bulk flows and the dynamics of voids in the Local Universe. We concentrate our study on the use of the Monge-Ampere-Kantorovitch reconstruction technique. Using peculiar velocities reconstructed from the 2MASS Galaxy Redshift Survey, and after comparison with the NGB-3k peculiar velocity catalog, we look in the details of these peculiar velocities. More particularly, we estimate the constraints that the peculiar velocities put on the cosmology. The information on dynamics that is included in reconstructed orbits of galaxies also allows us to have a much better prescription for defining and identifying voids in simulations and redshift catalogs. We present this new technique and how voids may give us additional constraints on cosmology with current and future surveys.