Cosmic Flows Project, Voyage to the Great Attractor
Helene Courtois



"Cosmic Flows" project is focused on producing observed galaxy distances for 30,000 galaxies with systematic errors below 2%, almost ten times the number currently known and a five-fold improvement in systematics. The resultant velocity field is providing initial conditions for constrained numerical cosmological simulations "CLUES". The observed and the simulated universe are then comparatively studied. This synergy of observations and theory distinguishes this program, and should lead to fundamental discoveries. Specifically, the program should give a definitive answer to an outstanding problem in cosmology since 1996 : the cause of the motion of 630 km/s of the CMB. On the path to this goal we are learning new informations on the dynamics of Large Scale Structures : the large coherent flows of galaxies away from voids and towards the Great Attractor region. We derive a most recent value for the Hubble constant at Ho=75 km/Mpc/s using SNIa. "Cosmic Flows" is bringing together unique expertise in radioastronomy, optical and space near-infrared surface photometry, theoretical astrophysics and numerical simulations. We tackle a frontier question: by learning our "cosmography", we look for where exactly are the Dark Energy and Dark Matter that dominate the cosmology?