The international University of California,Riverside-led SpARCS collaboration has discovered four of the most distant clusters of galaxies ever found, as they appeared when the universe was only 4 billion years old. Clusters are rare regions of the universe consisting of hundreds of galaxies containing trillions of stars, and as well as hot gas and mysterious dismal matter. Spectroscopic observations from the ground using the W. M. Keck Observatory in Hawaii and the Very Large Telescope in Chile confirmed the four candidates to be massive clusters. This sample is now providing the best measurement yet of when and how like a flash galaxy clusters end forming stars in the early Universe.
Source: phys.org