The youngest, most distant galaxy cluster ever discovered, CL J1001+0220, pushes the earliest cluster back to when the Universe was just 2.6 billion years old. Image credit: X-ray: NASA/CXC/Université Paris/T.Wang et al; Infrared: ESO/UltraVISTA; Radio: ESO/NAOJ/NRAO/ALMA.
There was a time in the Universe’s distant past where it was too young to contain the structures we see in it today. If we look back early enough, we should find no galaxy clusters, no galaxies, and even no stars. It takes millions or even billions of years for gravitation to pull matter together in order to form these giant, dense clumps of material, and without the right ingredients in the Universe, we wouldn’t get them early enough, or at all.
Thanks to a combination of observations from NASA’s Chandra X-ray telescope, the ESO’s UltraVISTA infrared telescope and the ALMA radio telescope, scientists have just announced the discovery of the most distant galaxy cluster ever: CL J1001+0220. Its light is only now arriving after an 11.2 billion year journey, making it the earliest structure this large ever discovered.
This cluster isn’t only remarkable for becoming the newest cosmic record-holder for an object so large at such early times, however. There are other galaxy clusters — some of which are much, much larger — discovered at a lookback time of up to ten billion years ago. But in all of those cases, the centers of these clusters already contain giant elliptical galaxies at their cores.