Using data from the COSMOS-Web survey — the largest single observing program ever conducted by the James Webb Space Telescope — astronomers have produced the most detailed map ever assembled of the cosmic web, the vast network of dark matter filaments, galaxy clusters, and supervoid regions that forms the large-scale skeleton of the observable universe, according to a study published in The Astrophysical Journal.
What the Cosmic Web Actually Is
The cosmic web is not a metaphor. It is the actual three-dimensional structure of matter in the universe — a network of filaments made predominantly of dark matter, laced with ordinary gas and studded with galaxy clusters at every intersection, separated by enormous voids hundreds of millions of light-years across where almost nothing exists. Every galaxy, including the Milky Way, sits somewhere within this web. The structure formed in the first billion years after the Big Bang, when gravitational collapse began pulling matter into the patterns we observe today.
Prior maps of the cosmic web relied on ground-based telescopes with limited depth and resolution. Webb's infrared sensitivity, combined with its position above Earth's atmosphere, allowed the COSMOS-Web team to map 164,000 galaxies across a patch of sky roughly the size of the full moon — but extending billions of light-years in depth, into regions no previous telescope had reached with this level of detail.
What the New Map Reveals
The map traces the growth of large-scale structure from approximately one billion years after the Big Bang to the present day, covering 13.7 billion years of cosmic evolution in a single dataset. Researchers at the University of California, Riverside, who led the analysis, identified thousands of previously unmapped filaments and catalogued dozens of new protoclusters — the seeds of the massive galaxy clusters observable in the modern universe.
"The jump in depth and resolution is truly significant," said a lead researcher at UC Riverside involved in the study. "We're not just seeing more galaxies. We're seeing the connective tissue between them for the first time at this scale."
The full galaxy catalog, density maps, and a time-lapse visualization of cosmic web growth across the complete dataset are publicly available through the Mikulski Archive for Space Telescopes, operated by the Space Telescope Science Institute in Baltimore, Maryland.
Houston's Role in the Discovery
The James Webb Space Telescope is managed by NASA's Johnson Space Center in Houston, Texas, in partnership with the Space Telescope Science Institute and the European Space Agency. Engineers at Johnson monitored the observing runs that produced the COSMOS-Web data in real time, and several researchers affiliated with the University of Texas system contributed to the data reduction pipeline used to process raw infrared observations into the final galaxy catalog.
The COSMOS-Web survey was designed before Webb launched in December 2021, specifically to maximize the telescope's ability to map large-scale structure. Winning the telescope time required — hundreds of hours of prime observation — required a competitive proposal process that the core team had begun developing as early as 2019, more than two years before launch.
Dark Energy in the Crosshairs
The next phase of analysis will focus on what the density maps reveal about dark energy — the poorly understood force that appears to be accelerating the expansion of the universe. By measuring how the cosmic web's filaments have grown or failed to grow over 13.7 billion years, researchers hope to place tighter constraints on dark energy's properties than any previous dataset has allowed.
A separate team at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, is applying machine learning tools to the COSMOS-Web catalog to identify potential signals of early cosmic structures that formed before the epoch covered by the survey, pushing the analysis window deeper into the universe's infancy than Webb can directly observe.
"Webb was designed to answer questions we already had," said a cosmologist at Princeton University who was not involved in the study but reviewed the findings for comment. "What it's doing now is generating questions we didn't know we needed to ask."