James Webb mapped 164,000 galaxies to chart the cosmic web back a billion years

A team using the James Webb Space Telescope has produced a map of the cosmic web that traces the universe’s hidden scaffolding through 164,000 galaxies. The depth and resolution mean astronomers can now see the web at a time when the universe was only a few hundred million years old, an era that was previously out of reach. For the first time, the gravitational architecture that organizes everything visible can be studied at the epoch when galaxies themselves were still being assembled.

The cosmic web is the universe’s underlying skeleton. Dark matter flows along enormous filaments, drawing galaxies to the intersections and leaving vast voids between them. Decades of optical surveys have sketched its shape in our cosmic neighborhood, but the early universe was too faint and too distant for ground-based telescopes to resolve at this level of detail.

The dataset comes from COSMOS-Web, the largest General Observer program Webb has run to date, covering a patch of sky equivalent in size to three full moons. The new analysis, led by Hossein Hatamnia at the University of California, Riverside, used Webb’s near-infrared imaging to identify 164,000 galaxies across that patch and assign each one a redshift, the cosmological proxy that doubles as distance and age. The study appears in The Astrophysical Journal.

With those distances in hand, the team reconstructed the three-dimensional positions of the galaxies and traced the network of filaments connecting them. Structures that appeared as single blobs in Hubble surveys resolve into several distinct features in the Webb data, and the catalogue extends to redshift seven, light that left its source when the universe was less than a billion years old.

What makes the result possible is not just depth but coverage. Single pencil-beam deep fields, however sharp, miss the geometry because they sample too little sky. COSMOS-Web traded a small amount of per-galaxy depth for the wider field needed to actually see the filaments as filaments, not as isolated points.

The catalogue is not the final word. Identifying the cosmic web from galaxy positions still depends on assumptions about how galaxies trace the underlying dark matter, and the redshifts here are photometric, derived from broadband colors rather than the more precise spectra that would pin each galaxy to within a fraction of a percent. The team frames the release as a foundation for spectroscopic follow-up campaigns, not as a closed result.

The map matters because predictions from standard cosmology are sharpest in this kind of large-scale geometry. The web’s shape as it evolves from a near-uniform early universe to today’s clumpy one is a direct test of the dark-matter, dark-energy model. Any persistent gap between the simulated web and the one Webb actually sees at high redshift would point to physics still missing from the picture.

The catalogue, the analysis pipeline, and a video reconstructing 13 billion years of structural evolution have been released publicly alongside the paper, which appeared in May 2026 in The Astrophysical Journal. The Riverside team and the wider COSMOS-Web collaboration are already preparing the spectroscopic follow-up of the highest-redshift filaments scheduled for the second half of 2026, which will sharpen the redshift errors and allow cosmologists to compare the web’s geometry to dark-matter simulations galaxy by galaxy.