Record-Breaking Galaxy Cluster Confirms Dark Matter Universe

This image contains the most distant galaxy cluster, a discovery made using data from NASA’s Chandra X-ray Observatory and several other telescopes. The galaxy cluster, known as CL J1001+0220, is located about 11.1 billion light years from Earth in the constellation of Sextans and may have been caught right after birth — a brief, but important stage of cluster evolution never seen before. This is a composite image where X-rays are purple, infrared is red, green and blue and radio green. Image credit X-ray: NASA/CXC/Université Paris/T.Wang et al; Infrared: ESO/UltraVISTA; Radio: ESO/NAOJ/NRAO/ALMA.

The remote galaxy cluster was found in data from the COSMOS survey, a project that observes the same patch of sky in many different kinds of light ranging from radio waves to X-rays. This composite shows CL J1001+0220 (CL J1001, for short) in X-rays from Chandra (purple), infrared data from ESO's UltraVISTA survey (red, green, and blue), and radio waves from the Atacama Large Millimeter/submillimeter Array (ALMA) (green). The diffuse X-ray emission comes from a large amount of hot gas, one of the defining elements of a galaxy cluster, as described in the press release.
In addition to its extraordinary distance, CL J1001 is remarkable because of its high levels of star formation in galaxies near the center of the cluster. Within about 250,000 light years of the center of the cluster (its core), eleven massive galaxies are found and nine of those display high rates of formation. Specifically, stars are forming in the cluster core at a rate equivalent to about 3,400 Suns per year.
The large amount of growth through star formation in the galaxies in CL J1001 distinguishes it from other galaxy clusters found at distances of about 10 billion light years and closer, where little growth is occurring. These results suggest that elliptical galaxies in clusters may form their stars through more violent and shorter bursts of star formation than elliptical galaxies outside clusters.
The latest study shows that CL 1001 galaxy cluster may be undergoing a transformation from a galaxy cluster that is still forming, known as a "protocluster," to a mature one. Astronomers have never found a galaxy cluster at this precise stage. These results may also imply that star formation slows down in large galaxies within clusters after the galaxies have already come together during the development of a galaxy cluster.


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.

The light from the “El Gordo” galaxy cluster, ACT-CL J0102-4915, comes to use from over 7 billion years in the past. It’s incredibly massive at over 3 quadrillion suns, but the giant ellipticals are already formed and are much quieter and full of older stars than a “new” cluster would indicate. Image credit: NASA, ESA, J. Jee (University of California, Davis), J. Hughes (Rutgers University), F. Menanteau (Rutgers University and University of Illinois, Urbana-Champaign), C. Sifon (Leiden Observatory), R. Mandelbum (Carnegie Mellon University), L. Barrientos (Universidad Catolica de Chile), and K. Ng (University of California, Davis).

Thought to occur from the mergers of multiple large spiral galaxies, elliptical galaxies are:

• larger,
• with ultra-massive black holes,
• devoid of gas that forms new stars,
• and, comparatively, inundated with older stellar populations.

But when we look at this newest, youngest and most distant cluster, we find that there are 11 massive galaxies close to its core, and an incredible nine of them are forming new stars at an incredible rate.