JWST COSMOS-Web map 164,000 galaxies

The COSMOS-Web project has turned James Webb Space Telescope data into the clearest large-area view yet of how galaxies are arranged across the universe. The result is a map built from about 164,000 galaxies, drawn from the largest contiguous JWST survey so far and spread across a patch of sky roughly equal to three full moons. Researchers said the work lets them trace the “cosmic web” — the network of filaments, clusters and voids that organizes matter on the largest scales — back to when the universe was about one billion years old. The underlying study appeared in *The Astrophysical Journal*, and the team has also posted public data products and an interactive viewer online. ### What exactly did COSMOS-Web release? The COSMOS-Web team released a large-scale-structure map derived from JWST observations, alongside public survey products that include reduced mosaics, catalogs, photometric redshifts and an interactive field viewer. The project site describes COSMOS-Web as a 255-hour Cycle 1 JWST treasury program covering 0.6 square degrees with NIRCam and 0.2 square degrees with MIRI in parallel. (news.ucr.edu) The May 2026 research release focused on reconstructing the distribution of galaxies across cosmic time rather than publishing a single “pretty picture.” University of California, Riverside, which highlighted the work on May 11, said the map is the most detailed yet of the cosmic web and traces that structure across 13.7 billion years of cosmic history. (cosmos.astro.caltech.edu) ### Why does “164,000 galaxies” matter here? The 164,000 figure is the sample used to build the new cosmic-web reconstruction in the paper, not the total number of objects available in the broader COSMOS-Web data products. The paper summary says the researchers used about 160,000 galaxies with robust photometric redshifts, while UCR’s release described the result more broadly as a map tracing 164,000 galaxies. (news.ucr.edu) The project’s public release is larger than that. COSMOS-Web’s data-release page says it hosts photometric redshifts and physical properties for about 780,000 galaxies, and the project overview says the full survey is expected to contain about a million galaxies across cosmic time. ### How big is this map compared with earlier JWST work? COSMOS-Web covers a continuous 0.6-square-degree field in NIRCam, which NASA and the project describe as about the area of three full moons. (iopscience.iop.org) For JWST, that is unusually wide: the mission is often associated with very deep but relatively narrow observations, while COSMOS-Web was designed to combine width and depth. (cosmos2025.iap.fr) UCR said COSMOS-Web was the largest General Observer program selected for JWST. That scale matters because a wide field helps researchers follow large structures such as filaments, dense nodes and voids instead of seeing only small slices of them. ### What is the “cosmic web” they are mapping? The cosmic web is the large-scale arrangement of matter in the universe: dense filaments and clusters separated by vast low-density voids. (cosmos.astro.caltech.edu) In the UCR description, bright regions in the map mark dense filaments and clusters, while dark regions correspond to near-empty voids. (news.ucr.edu) Hossein Hatamnia, a graduate student at UC Riverside and Carnegie Observatories and lead author of the study, said JWST gave the team the “wide, deep view” needed to see that structure. The paper’s abstract says the reconstruction traces environmentally driven galaxy evolution up to about redshift 7, which corresponds to the universe’s first billion years. (news.ucr.edu) ### What can researchers and readers do with it now? The COSMOS-Web public data release site already hosts the survey mosaics, catalogs and interactive map viewer, and it says large-scale-structure density maps up to z = 7 are available under additional data products. That means astronomers can inspect the field directly and reuse the released measurements rather than waiting for a future mission archive cycle. (news.ucr.edu) The next step is continued analysis from the same survey. The project overview says COSMOS-Web was built to study reionization-era galaxies, massive galaxy evolution and dark-matter halo clustering, and the current release provides the wide-field framework for those follow-on papers. (cosmos.astro.caltech.edu) (cosmos2025.iap.fr)