Scientists using the James Webb Space Telescope have produced the highest-resolution map of dark matter to date, based on distortions in 250,000 galaxies. This map uncovers previously unseen cosmic structures and could deepen understanding of the universe's evolution. The achievement highlights dark matter's dominant role, comprising 85 percent of the universe's matter.
Astronomers led by Jacqueline McCleary at Northeastern University in Massachusetts have mapped dark matter by analyzing gravitational lensing effects on distant galaxies observed with the James Webb Space Telescope (JWST). The team examined a sky area slightly larger than the full moon, achieving a resolution twice that of prior Hubble Space Telescope maps and extending to more remote cosmic regions.
Dark matter, which does not emit detectable light, reveals itself through its gravitational influence on visible matter. By studying how this gravity warps the light from about 250,000 background galaxies—described as 'cosmic wallpaper' by Liliya Williams of the University of Minnesota—the researchers traced massive galaxy clusters and the connecting filaments of the cosmic web. Some of these features do not align with previous observations of luminous matter, suggesting they are primarily composed of dark matter.
"It is a very high-resolution picture of the scaffolding of this little corner of the universe," McCleary noted. Williams, who was not involved in the study, emphasized the method's superiority: "To identify many of these structures over a wide field, gravitational lensing is one of very, very few techniques, and definitely the best."
This mapping is significant because dark matter constitutes roughly 85 percent of the universe's total matter, shaping the formation of galaxies, clusters, and the cosmos at large. The data may refine cosmological parameters, including dark energy's strength, and explore how galaxies and their dark matter halos evolve. "Not only is it an observational coup, but in turn it’s going to enable a lot of other analysis—cosmological parameter constraints, the connection between galaxies and their dark matter haloes and how they grow and evolve over time," McCleary said.
Preliminary results align with the standard lambda-CDM model of cosmology, though deeper analysis is ongoing. "Although at a glance it’s a match for lambda-CDM, I’m not giving up yet—I’m withholding judgment until our analysis is finished," McCleary added. The findings appear in Nature Astronomy (DOI: 10.1038/s41550-025-02763-9).