2024NatAs...8.1610V

The structure in the Universe is believed to have evolved from quantum fluctuations seeded by inflation in the early Universe. These fluctuations lead to density perturbations that grow via gravitational instability into large cosmological structures. In the linear regime, the growth of a structure is directly coupled to the velocity field because perturbations are amplified by attracting (and accelerating) matter. Surveys of galaxy redshifts and distances allow one to infer the underlying density and velocity fields. Here, assuming the lambda cold dark matter standard model of cosmology and applying a Hamiltonian Monte Carlo algorithm to the grouped Cosmicflows-4 (CF4) compilation of 38,000 groups of galaxies, the large-scale structure of the Universe is reconstructed out to a redshift corresponding to ∼30,000 km s^–1. Our method provides a probabilistic assessment of the domains of gravitational potential minima: basins of attraction (BoA). Earlier Cosmicflows catalogues suggested that the Milky Way Galaxy was associated with a BoA called Laniakea. With the newer CF4 data, there is a slight probabilistic preference for Laniakea to be part of the much larger Shapley BoA. The largest BoA recovered from the CF4 data is associated with the Sloan Great Wall, with a volume within the sample of 15.5 × 10⁶ (h^–1 Mpc)³, which is more than twice the size of the second largest Shapley BoA.