A Surprisingly Calm and Remote Galaxy Cluster Has Been Discovered

• The finding of the most distant galaxy cluster with a specific key attribute - as outlined in our news release - sheds light on how these massive formations arose and why the cosmos appears the way it does now.

Image credit: X-ray: NASA/CXC/MIT/M. Calzadilla; UV/Optical/Near-IR/IR: NASA/STScI/HST; Image processing: N. Wolk

• SPT-CL J2215-3537 (SPT2215 for short) is depicted in this composite image in X-rays from NASA's Chandra X-ray Observatory (blue) and a combination of ultraviolet, optical, and infrared light from NASA's Hubble Space Telescope (cyan and orange). Astronomers employed Chandra, the NSF/DOE South Pole Telescope, the Dark Energy Survey project in Chile, and NASA's Spitzer Observatory to discover this distant and unusually young galaxy cluster. The findings have been published in three papers.

• SPT2215 is around 8.4 billion light-years away from Earth. This suggests it was observed when the universe was just 5.3 billion years old, as opposed to its present age of 13.8 billion years. While many clusters have been spotted at such a great distance, SPT2215 has a unique feature that makes its location extremely noteworthy. SPT is "relaxed," which means it has not been disrupted by violent collisions with other clusters of galaxies.

• Galaxy clusters, which are some of the largest formations in the cosmos, expand over time by merging with other galaxy clusters or groups, generating asymmetries or sharp features in the cluster's gas. Given enough time to "relax," the gas, as seen with SPT2215, can take on a smooth, peaceful appearance. Until the discovery of SPT2215, researchers had never discovered a relaxed galaxy cluster this far away. In fact, scientists were skeptical that they would uncover a peaceful galaxy cluster at this time in the cosmos because they are normally still through the turbulence of mergers with other clusters or groupings of galaxies as they grow in size.

• Another intriguing characteristic of SPT2215 is the evidence for massive star development in its core. SPT2215 has a huge galaxy in the center, which is surrounded by a supermassive black hole. Scientists believe that much of the heated has cooled to the point that new stars can form, without outbursts caused by the black hole providing a heating source that inhibits most of this cooling. This tackles the long-standing subject of how much black holes impede or assist star formation in their environs.

• The Chandra program is managed by NASA's Marshall Space Flight Center. The Smithsonian Astrophysical Observatory's Chandra X-ray Center is based in Cambridge, Massachusetts, and the flight operations are based in Burlington, Massachusetts.

All creadit goes to NASA.