The James Webb Space Telescope targeted the remote TGSSJ1530+1049 system, capturing a moment just 1.5 billion years after the Big Bang when a massive galaxy and its central supermassive black hole were emerging simultaneously.
Rather than finding a single galaxy, researchers from Leiden University and Oxford discovered a compact cluster consisting of at least six separate galaxies. Four of these are already quite massive, collectively harboring hundreds of billions of solar masses of stars within a region only a few tens of thousands of light-years across. This extreme density marks the system as one of the most crowded clusters of massive galaxies ever identified in the early universe.
While previous radio observations had hinted at an active black hole, Webb revealed that the environment was far more complex than initially thought. Oxford’s Aayush Saxena noted, "We found not just a single galaxy, but an entire complex of at least six." Leiden's Roderik Overzier added that such structures are protoclusters—the precursors to today's giant galaxy clusters.
A young supermassive black hole sits at the center of this structure. Its growth appears to be fueled by the ongoing process of galactic mergers. Krisztina Gabányi from Budapest University explained that a network of radio telescopes provided a clear picture: radio emissions occur as matter falls into the hole, with a portion of it being ejected at immense speeds.
Huub Röttgering emphasized the unique nature of the discovery, stating, "We can simultaneously monitor the formation of a giant galaxy and the growth of the black hole at its core." The findings have been published in The Open Journal of Astrophysics and Astronomy & Astrophysics, based on data gathered by the James Webb Space Telescope.
Located more than 12 billion light-years away, these observations provide a direct look at how the ancestors of the largest galaxies we see today were assembled in the young universe.
