Partitioning the universe into gravitational basins using the cosmic velocity field

Understand

This letter presents a new approach using the cosmic peculiar velocity field to characterize the morphology and size of large scale structures in the local Universe.

• The algorithm developed uses the three-dimensional peculiar velocity field to compute flow lines, or streamlines.
• The local Universe is then partitioned into volumes corresponding to gravitational basins, also called watersheds, among the different end-points of the velocity flow lines.
• This new methodology is first tested on numerical cosmological simulations, used as benchmark for the method, and then applied to the {\it Cosmic-Flows} project observational data in order to to pay particular attention to the nearby superclusters including ours.