# Partitioning the universe into gravitational basins using the cosmic velocity field

## TL;DR

This paper introduces a novel method to delineate large-scale cosmic structures by analyzing the cosmic velocity field to identify gravitational basins, enhancing understanding of the universe's morphology.

## Contribution

The paper develops a new algorithm that uses the cosmic velocity field to partition the universe into gravitational basins, validated on simulations and applied to observational data.

## Key findings

- Successfully applied the method to simulations and real data.
- Identified gravitational basins corresponding to known superclusters.
- Provides a new way to analyze large-scale cosmic structure.

## Abstract

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. More extensive tests on both simulated and observational data will be discussed in an accompanying paper.