The Enigma of an Ancient Galaxy Cluster in the Early Universe




A surprisingly large collections of galaxies (red dots in center) stands out at a remarkably great distance in the composite image above combining infrared and visible-light observations. In a twist, this apparent ancestor to today's grouped galaxies looks shockingly modern. Called CLG J02182-05102, the ancient cluster is dominated by old, red and massive galaxies, typical of present-day clusters.

"We are seeing something already aged and red like a younger version of the Coma Cluster from a distant, bygone era," said Casey Papovich, lead author of the study and an assistant professor of physics and astronomy at Texas A&M University in College Station. Papovich added, "it is as though we dug an archeological site in Rome and found pieces of modern Rome in amongst the ruins."
The Coma Cluster of today has had billions of more years to develop. Most of the galaxies that inhabit the central portion of the Coma Cluster are ellipticals. Both dwarf, as well as giant ellipticals, are found in abundance.

ClG J02182-05102 might have indeed been ahead of its time. Just as Rome was the world's biggest city more than 2,000 years ago with a population of about a million residents, observed Papovich – a figure not again matched until the early 1800s in London – so too was this galactic grouping an advanced civilization for so early an era in the developing universe.

Galaxy clusters are the largest gravitationally bound structures in the universe and are thought to have formed piecemeal over cosmic time. For now, ClG J02182-05102 is the only known galactic grouping so far away in the past, and studying it will help researchers understand the overall history of how galaxies congregate and evolve.


Image credit: NASA/JPL-Caltech/Subaru


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