James Webb maps largest-ever cosmic web

Astronomers using the James Webb Space Telescope have produced what researchers and institutional releases describe as the most detailed map yet of the universe’s cosmic web, the vast large-scale structure that links galaxies, clusters and nearly empty voids. The work appeared in *The Astrophysical Journal* on May 6, 2026, and was later highlighted by Live Science on May 18. The map comes from COSMOS-Web, the largest James Webb General Observer survey selected so far, according to the project’s university partners. The reconstruction traces galaxy structure across about 13.7 billion years of cosmic history, back to when the universe was less than 1 billion years old. ### What is the “cosmic web” researchers say Webb has mapped? The cosmic web is the universe’s large-scale framework of filaments, sheets, clusters and voids, according to UC Riverside and Rochester Institute of Technology releases on the study. Galaxies do not sit randomly in space; they gather along denser strands, while large emptier regions open between them. (news.ucr.edu) Live Science described the result as a reconstruction of the cosmos’s “skeleton,” showing how galaxies have evolved since the universe’s infancy and how they fall together into that larger structure. That matters because the web is the backdrop against which galaxies grow, merge and stop forming stars. ### What did Webb actually add that earlier surveys could not? (news.ucr.edu) COSMOS-Web used Webb’s infrared sensitivity and sharpness to detect faint, distant galaxies that earlier observatories could not see as clearly, UC Riverside said. That allowed the team to map structure farther back in time and through dust, extending the reconstruction to epochs when the universe was under a billion years old. (cnas.ucr.edu) The survey covered a contiguous patch of sky about the size of three full Moons, according to UC Riverside. ScienceDaily’s summary of the university release said the team analyzed more than 164,000 galaxies, giving the project both unusual depth and breadth for a Webb-era map of large-scale structure. ### Who led the study, and what did they say they found? (news.ucr.edu) Hossein Hatamnia, a graduate student at the University of California, Riverside and Carnegie Observatories, was the lead author, UC Riverside and RIT said. Hatamnia said COSMOS-Web was designed from the start to deliver the “wide, deep view” needed to see the cosmic web. Jeyhan Kartaltepe, a professor at Rochester Institute of Technology and a co-leader of the broader COSMOS survey, said the data provided an “exquisite three-dimensional view” of the universe from very early cosmic time to today. (news.ucr.edu) RIT said the reconstruction suggests large-scale structure helps drive galaxy evolution by boosting early mass assembly in dense regions and later suppressing star formation in lower-mass systems. ### Why are researchers calling this map unusually significant? The map is being described as both the largest and the most detailed of its kind because it combines a wide survey area with deep infrared observations from Webb, according to Live Science and the university releases. In practical terms, that means astronomers can compare galaxies not just one by one, but by the environments they occupy across cosmic time. (rit.edu) The visualization itself is a slice through nearly 14 billion years of history, with the present day at one end and progressively earlier epochs farther out, the releases said. Bright yellow regions mark dense filaments and clusters, while darker regions indicate the near-empty voids between them. ### What comes next from the COSMOS-Web team? (cnas.ucr.edu) RIT said the current paper follows the team’s earlier release of the largest view yet of the universe and accompanies the release of one of the most detailed high-resolution dark-matter maps yet produced. That suggests the COSMOS-Web dataset will continue generating follow-up papers on structure formation and galaxy evolution. (news.ucr.edu) The study is already available in *The Astrophysical Journal*, and the project’s institutional summaries from UC Riverside and Rochester Institute of Technology provide the named researchers, images and survey details behind the result. (news.ucr.edu) (rit.edu)