The ancestors of galaxy clusters, the largest structures in the universe, have been identified by a team of astronomers including Brian Lemaux, who is affiliated with the UC Davis Department of Physics and Astronomy. Galaxies in the newly identified protoclusters are surprisingly sparse and dim, which may be why they have been so difficult to find until now. The work was published June 15 in Nature.
The first galaxy clusters formed as matter began to clump together after the Big Bang. Galaxies formed within them and eventually, clusters and superclusters contained thousands of galaxies bound together by gravity. Conditions inside the cluster influence the size, shape and color of galaxies.