Dynamic cosmography of the local Universe: Laniakea and five more watershed superclusters

Abstract

This article delivers the dynamical cosmography of the local Universe within z = 0.1 (1 giga light-years). We exploited the gravitational velocity field computed using the CosmicFlows-4 catalog of galaxy distances in order to delineate superclusters as watersheds, publishing for the first time their size, shape, main streams of matter, and the location of their central attractor. We confirm the size of Laniakea, our home supercluster, to be 2 × 106 (Mpc h−1)3. We dynamically define five more known superclusters in the same way as Laniakea: Apus, Hercules, Lepus, Perseus-Pisces, and Shapley. Additionally, we found the central repellers of the Bootes and Sculptor voids, and based on our analysis, the Dipole and Cold Spot repellers appear as a single gigantic entity. Interestingly, the observed superclusters are an order of magnitude larger than the theoretical ones predicted by cosmological ΛCDM simulations.