Webb telescope produces most detailed map of the cosmic web with 164,000 galaxies

A team of astronomers at the University of California, Riverside, led by PhD student Hossein Hatamnia, published on May 12, 2026 in the Astrophysical Journal the most detailed map of the cosmic web to date. The map is built from data of the COSMOS-Web program, the largest observing program ever conducted by the James Webb Space Telescope, covering a patch of sky roughly the size of three full Moons. The analysis identifies 164,000 galaxies and assigns each a redshift, serving simultaneously as a measure of distance and age, with the most distant objects reaching z ~7, corresponding to a universe about one billion years old.

The cosmic web is the name for the largest structure in the known universe, made up of long filaments of gas and dark matter linking dense nodes that contain thousands of galaxies, with voids of tens of millions of light-years between filaments. The existence of this web was predicted as far back as the 1980s from cold dark matter theory, but its detailed geometry in the most distant epochs of the universe has until now been inferred mostly from simulations, not direct observation. The Hatamnia team is the first to sample, in a single dataset, the full range from contemporary galaxies in our neighbourhood to galaxies formed when the universe was less than ten percent of its current age.

Methodologically, COSMOS-Web uses the NIRCam near-infrared camera operating at wavelengths between 0.6 and 5 micrometres. This spectral range is critical for observing galaxies at high redshift, because cosmic expansion shifts their visible light towards the infrared. The Hatamnia team computed a photometric redshift for each of the 164,000 galaxies, using comparisons against spectral energy distribution models, a process with an estimated error of about 5 to 10 percent for individual objects, but proportionally accurate in a statistical sample of this size.

What the new map does NOT change in the cosmological picture

While the result is significant in scope, it is worth separating what it demonstrates from what it does not. The map confirms that the cosmic web exists even in the very early universe, in line with the standard Lambda CDM cold dark matter model. It is not, therefore, a discovery of new physics, nor does it challenge the assumption that dark matter is the dominant gravitational driver of large-scale structure formation. What the map does offer is the most precise empirical framework yet for comparison with numerical simulations, allowing tests of how accurately existing galaxy-formation models predict the density, distribution and evolution of filaments over time.

A second limitation is the size of the sky covered. Three full Moons sounds like a lot but represents about 0.005 percent of the entire sky. That means conclusions about large structures rest on a local sample, which can be biased if the COSMOS-Web region happens to be atypical in galaxy density, a phenomenon known in cosmology as cosmic variance. Future, broader maps from the Rubin Observatory in Chile from 2026 onward, and from the European Space Agency’s Euclid mission launched in 2023, will need to confirm or qualify the COSMOS-Web findings by covering far larger sky areas.

The Hatamnia team has also publicly released the full galaxy catalogue with photometric redshifts, the analysis code and a video showing the evolution of the structure across 13.7 billion years of cosmic history. According to ESA and NASA, the Webb telescope by May 2026 had completed more than 4,500 observing sessions, of which COSMOS-Web is individually the largest. The next major spectroscopic campaign, aimed at further refining redshifts for a subset of about 30,000 of the most interesting galaxies from the map, is planned for the second observing cycle in autumn 2026 and spring 2027.

From the perspective of galaxy evolution, the new results allow, for the first time, a quantitative tracking of where galaxies formed in relation to large filaments and dark-matter nodes. Earlier studies suggested that galaxies in dense regions age and stop forming stars earlier than those in sparser environments. The COSMOS-Web map shows, according to Hatamnia, that this phenomenon can be traced back as far as redshift z ~3, corresponding to a universe about two billion years old, while deeper in the past the link between environment and evolution becomes less consistent. Pinning down exactly where that inconsistency comes from, whether from statistics, lack of resolution, or a real physical difference, is the next round of research using the COSMOS-Web data.