Shapley basin

A supercluster defined by motion: the region whose galaxies all flow toward the Shapley Supercluster, the most massive concentration of galaxies near us. The Coma Cluster falls inside it. One of the five such basins around Laniakea.

Its outline is the watershed Dupuy and Courtois (2023) traced through the Cosmicflows-4 velocity field, reconstructed from the measured distances of about 56,000 galaxies on a grid of 37-million-light-year cells, so its edges are approximate. Distances use this map's Planck Hubble constant; on Cosmicflows' own they are a tenth smaller. The threads are streamlines of the same field, the paths matter is moving along; their moving dashes show which way, not how fast.

Across

about 1.19 billion ly

End to end

1.74 billion ly

Attractor

746 million ly from the Sun

The Shapley Supercluster or Shapley Concentration is one of the largest concentrations of galaxies in the observable universe that forms a bound, gravitationally interacting unit, thereby pulling itself together instead of expanding with the universe. It appears as a striking overdensity in the distribution of galaxies in the constellation of Centaurus.

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