Astronomers using the South Pole Telescope report that they have discovered the most massive galaxy cluster yet seen at a distance of 7 billion light-years. The cluster (designated SPT-CL J0546-5345) weighs in at around 800 trillion Suns, and holds hundreds of galaxies.
“This galaxy cluster wins the heavyweight title. It’s among the most massive clusters ever found at this distance,” said Mark Brodwin, a Smithsonian astronomer at the Harvard-Smithsonian Center for Astrophysics. Brodwin is first author on the paper announcing the discovery, which appeared in the Astrophysical Journal.
Redshift measures how light from a distant object has been stretched by the universe’s expansion. Located in the southern constellation Pictor (the Painter), the cluster has a redshift of z=1.07. This puts it at a distance of about 7 billion light-years, meaning we see it as it appeared 7 billion years ago, when the universe was half as old as now and our solar system didn’t exist yet.
