JWST COSMOS-Web maps 14 billion years

On May 11, 2026, researchers working with the James Webb Space Telescope’s COSMOS-Web survey said they had produced their most detailed map yet of the universe’s large-scale structure. The map traces how galaxies are arranged across roughly 13.7 billion years of cosmic history, reaching back to when the universe was less than 1 billion years old. The work draws on COSMOS-Web, a 255-hour JWST program designed to survey a wide patch of sky and track galaxies across deep time. The underlying paper was published in *The Astrophysical Journal* in 2026. ### How far back does this map actually go? The 2026 paper describes a reconstruction of large-scale structure “up to z ~ 7,” an astronomical redshift corresponding to the universe’s first billion years. In practical terms, that means the map does not just show nearby clusters and voids but extends into an era when early galaxies were still assembling. COSMOS-Web was built for that kind of reach. The project page says the survey was designed to detect thousands of galaxies during the epoch of reionization, roughly redshift 6 to 11, and to map environments on scales large enough to reduce the effects of cosmic variance. ### What did the team map? The University of California, Riverside said the new result traces the “cosmic web,” the network of dense filaments, galaxy clusters and relatively empty voids that make up the universe’s large-scale structure. The release described the map as the most detailed one yet produced from the COSMOS-Web data set. The paper says the reconstruction used COSMOS-Web observations to trace environmentally driven galaxy evolution across cosmic time. That gives astronomers a way to compare where galaxies sit — in dense regions, filaments or emptier zones — and how those environments changed over billions of years. ### How large is the COSMOS-Web survey behind it? COSMOS-Web is the largest JWST survey so far, according to the paper and the project description. The official COSMOS-Web page says the program mapped a contiguous 0.6 square-degree area with JWST’s Near Infrared Camera and a non-contiguous 0.2 square-degree area with the Mid-Infrared Instrument in parallel. The same project page says the survey is expected to contain about 1 million galaxies across cosmic time. Its first public data release hosts reduced mosaics, photometric catalogs, redshifts and physical properties for about 780,000 galaxies, along with an interactive map viewer over the field. ### Why are astronomers focusing on structure instead of single galaxies? Bahram Mobasher of the University of California, Riverside said in the university release that galaxy evolution is shaped not only by internal processes but also by surroundings. Mapping where galaxies sit inside filaments, clusters and voids lets researchers test how environment influenced their growth at different epochs. Hossein Hatamnia, the paper’s lead author, and co-authors wrote that COSMOS-Web’s depth and area make it possible to examine those environmental effects much earlier in cosmic history than before. The paper presents that as a first view of how large-scale environment and galaxy evolution connect from the epoch of reionization toward the present. ### Where can researchers and the public see the data? The COSMOS-Web DR1 site says large-scale-structure density maps up to redshift 7 were added to the public release on December 10, 2025. The same portal includes image mosaics, catalogs and an interactive viewer covering the full field. On May 4, 2026, the project updated the catalog to version 1.1 and added multi-band morphological measurements, according to the release notes on the data site. Jeyhan Kartaltepe of Rochester Institute of Technology and Caitlin Casey of the University of California, Santa Barbara are listed as the survey’s principal contacts for COSMOS-Web.