July 23, 2026 report JWST captures rare glimpse of early black hole growing inside network of young galaxies Shreejaya Karantha Author Sadie Harley Scientific Editor Robert Egan Senior Editor Astronomers using the James Webb Space Telescope have captured one of the clearest views yet of how an early supermassive black hole may grow within a network of young galaxies. The compact active galaxy, seen just a billion years after the Big Bang, lies beside a 12,000-parsec-long filament containing multiple galaxies that are expected to merge within a few hundred million years. The findings, posted to the arXiv preprint server on July 6, suggest astronomers may be witnessing a short-lived phase in the evolution of rapidly growing black holes while also shedding light on how the first massive galaxies assembled in the early universe.

Too big for its galaxy Since JWST began operating, astronomers have found a population of compact, actively feeding black holes in galaxies from the universe's first billion years. Many of these black holes appear far too massive for their host galaxies, with some appearing 10 to 100 times heavier than expected. This particular black hole, in a galaxy known as GN-77652, is observed at a redshift of 5.23.

It weighs about 11 million solar masses, while its host galaxy contains only around 170 million solar masses worth of stars, placing it at roughly 300 times the mass expected from a relation seen between black holes and their galaxies in the nearby universe. Crowded home Led by Giulia Tozzi of the Max Planck Institute for Extraterrestrial Physics, the team used JWST's NIRSpec integral field spectrograph, as part of the BlackTHUNDER program, alongside deep NIRCam imaging to map the region around GN-77652 in detail. What they found was a bustling environment containing four additional galaxy-sized clumps of gas and stars, labeled B, C, D and E, all sitting at essentially the same redshift.

These clumps were spread across the filament at distances of roughly 2.4 to 11.6 kiloparsecs from GN-77652. Interestingly, GN-77652 is not the most massive galaxy in the group. Sources B and D are each 10 times heavier in stars.

Gas across the whole structure appears to converge toward source B, near the center of the complex, hinting that the entire system may eventually merge into one. The five sources differ by up to an order of magnitude in stellar mass, star formation rate and chemical enrichment, suggesting each component is at a different stage of evolution. GN-77652 itself shows a shallow, resolved velocity gradient consistent with a small rotating gas disk.

The team explains in the paper that this unique feature, confirmed in only a handful of these compact black hole hosts so far, is "consistent with dominant gravity driving"—the same pattern seen in normal star-forming galaxies at these redshifts—suggesting GN-77652 behaves more like a settled galaxy than a violently disturbed one. Signs of a twin? The most striking result comes from source B, sitting just 2.4 kiloparsecs (in projection) from GN-77652.

The diagnostic emission-line ratios there point to gas being ionized by something more energetic than starlight alone.