JWST images XLSSC 122, most distant galaxy cluster acting as strong gravitational lens, fully formed at cosmic noon
Astronomers found a galaxy cluster that should not look this finished. JWST imaged XLSSC 122, over 10 billion light-years away, already large and organized when such structures were thought to be barely forming. Now the most distant cluster known to bend light as a strong gravita
Astronomers have found a galaxy cluster that looks far too finished for its age. Using the James Webb Space Telescope, a team led by IPAC at Caltech imaged a cluster called XLSSC 122, sitting more than 10 billion light-years away. At that distance we are seeing it as it was during an era astronomers call cosmic noon, when galaxy clusters were thought to be only starting to come together. Instead this one already appears large and well organized, more like the mature clusters we see in the nearby universe today. The cluster is now the most distant example known of a structure massive enough to act as a strong gravitational lens, its gravity bending and magnifying the light of even more distant galaxies behind it. That makes it both a discovery in itself and a new tool for studying the early universe. The reason it matters is timing: current models describe how cosmic structure assembles from small clumps into large clusters over billions of years, and finding something this organized this early suggests the process can run faster than expected in places. Three research papers describing the cluster, its lensing and its internal light were presented to the astronomical community this month.