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yesterday

Webb Delivers Sharpest Contiguous Map of Dark Matter’s Cosmic Web

Using weak‑lensing distortions in 250,000 galaxy shapes, the team created a high‑precision dataset that will underpin forthcoming cosmology checks.

An image containing nearly 800,000 galaxies from NASA's James Webb Space Telescope (JWST), overlaid with dark matter clumps shown in blue.
(Credit: NASA/dima_zel)
Image
A new, highly detailed map powered by JWST data reveals the invisible dark matter structure of our universe. By tracking how gravity bends light, researchers mapped out where invisible mass is located. The contours show regions of equal density and the blue colors mark the highest concentrations of dark matter in this 0.54-square-degree section of sky. Credit: Dr Gavin Leroy/COSMOS-Webb collaboration

Overview

  • The COSMOS‑Webb collaboration reported the results in Nature Astronomy on January 26, detailing an international effort spanning institutions including Durham University, NASA’s Jet Propulsion Laboratory, École Polytechnique Fédérale de Lausanne, and Northeastern University.
  • Covering a contiguous 0.54‑square‑degree region in the Sextans constellation, the map draws on roughly 255 hours of JWST observations that identified nearly 800,000 galaxies and enabled about 250,000 shape measurements.
  • The result is roughly twice as sharp as prior dark‑matter maps from Hubble or ground‑based surveys, producing the most detailed contiguous weak‑lensing mass map to date.
  • Filamentary bridges, clusters, and faint low‑mass groups emerge in unprecedented detail, including mass concentrations with weak or no luminous counterparts.
  • Initial comparisons broadly align with the standard ΛCDM model, with deeper analyses underway and wider but lower‑resolution surveys by ESA’s Euclid and NASA’s Roman expected to extend these tests across much larger sky areas.