The universe has a skeleton. Astronomers call it the cosmic web — a vast scaffolding of gas filaments, dark matter, and galaxy clusters that organizes everything that exists across billions of light-years. Now, using the James Webb Space Telescope, researchers have mapped it in greater detail than ever before.
The resulting chart draws on a 255-hour survey covering a patch of sky roughly three times the size of a full moon, cataloging 164,000 galaxies across 13 billion years of cosmic history. What it reveals about how those galaxies were born — and how they died — is only beginning to come into focus.
The largest map of the cosmic web ever made
The COSMOS-Web survey is the biggest JWST program conducted to date — 255 hours of observation time covering a contiguous patch of sky roughly the size of three full moons. That effort produced a catalog of 164,000 galaxies, now publicly available to researchers around the world. The scale alone sets it apart from anything that came before.
Size isn’t the only improvement, though. Compared to the previous benchmark — the COSMOS2020 survey assembled using the Hubble Space Telescope and other facilities — COSMOS-Web delivers sharper redshift precision, the measurement astronomers use to gauge cosmic distance and time based on how light stretches toward redder wavelengths as it travels across the universe. It also captures galaxies that Hubble-era surveys simply missed: fainter objects, lower-mass systems, galaxies so distant they existed when the universe was still in its infancy.
COSMOS2020 carried another flaw worth noting. It tended to overestimate the density of already-crowded cosmic regions while underestimating the emptiness of sparse ones. JWST’s map corrects that imbalance, preserving relative contrast across the full range of cosmic environments.
What the cosmic web actually is
The cosmic web is the largest known structure in existence — a vast, interconnected scaffolding of gas filaments, dark matter sheets, galaxy clusters, and enormous empty voids that organizes all matter across the observable universe. Everything that exists sits somewhere within it.
That framework isn’t passive. It actively shapes where galaxies form, how quickly they grow, and whether they ultimately survive or fade. Understanding the web means understanding the full arc of cosmic history.
One of JWST’s most consequential contributions is its ability to resolve this structure at extraordinary distances. Astronomers can now trace the cosmic web back to a time when the universe was only a few hundred million years old — an era that was, as UCR professor Bahram Mobasher noted in a statement, “essentially out of reach before JWST.”
How the web shaped the rise and fall of star formation
In the early universe, the densest regions of the cosmic web were engines of growth. Galaxies packed into crowded filaments and clusters formed stars at a furious pace, drawing on abundant gas and the gravitational pressure of their surroundings. The universe was, in a sense, at its most productive.
That era is long over. The peak of cosmic star formation is many billions of years behind us, and the universe has been winding down ever since. COSMOS-Web adds new detail to how that transition actually unfolded — who drove it, where, and when.
“We show how the cosmic web helped shape galaxy growth before, during, and after that peak era,” study co-author Hossein Hatamnia told Live Science. The pattern is notable in its reversal: dense regions that once accelerated galaxy growth are now the places most strongly associated with galaxies that have gone quiet, their star-forming days effectively over.
Two mechanisms that kill galaxies
The shutdown of star formation — what astronomers call quenching — doesn’t happen through a single process. The COSMOS-Web findings point to two distinct mechanisms, each dominant at a different point in cosmic history.
The first is tied to mass. When a galaxy’s dark matter halo reaches roughly one trillion solar masses, it heats the surrounding gas to temperatures that prevent it from cooling and collapsing into new stars. Supermassive black holes contribute to the same outcome through a different route: their near-light-speed jets blast surrounding gas with enough energy to disrupt star formation entirely. Mass-driven mechanisms were the dominant quenching force up until about seven billion years ago — roughly the halfway point in the universe’s current age.
After that threshold, the picture shifts. Environment takes over as the primary driver. Neighboring structures can strip galaxies of their cold gas reserves, or simply prevent new cold gas from accumulating. Without that raw material, star formation stalls. The galaxy doesn’t explode or collapse — it just quietly runs out of fuel.
Why this leap in resolution matters
Previous cosmic surveys, even the best Hubble-era maps, rendered many distant galaxies as indistinct smudges. JWST changes that. What were once blurry blobs are now resolved into distinct, ancient, dim galaxies — individual objects with measurable properties rather than unresolvable noise.
That qualitative jump matters for more than aesthetic reasons. Sharper resolution means more reliable data on galaxy properties, better distance estimates, and a more faithful picture of how structure varies across the universe. The map doesn’t just show more galaxies — it shows them more accurately.
The findings were published May 6 in The Astrophysical Journal by an international team led by researchers from the University of California, Riverside. The full 164,000-galaxy catalog has been made publicly available, meaning astronomers worldwide can build on this foundation immediately.
What comes next
A map of this scale and precision is, in one sense, an answer — but it functions more as a starting point. Researchers can now cross-reference the catalog against other datasets, test competing models of galaxy evolution, and probe specific cosmic epochs in ways that were previously impractical.
The ability to observe the cosmic web when the universe was only a few hundred million years old opens questions that weren’t even well-formed before. How did the earliest filaments take shape? How precisely did environment and mass interact over time? What triggered the first wave of star formation in dense regions?
JWST is still early in its operational life. As more survey data accumulates and analysis deepens, the picture of how the universe built — and then quietly dismantled — its galaxies will continue to sharpen.