An ultra-high-resolution map of (dark) matter

April 2026 • 2026NatAs..10..573S

Authors • Scognamiglio, Diana • Leroy, Gavin • Harvey, David • Massey, Richard • Rhodes, Jason • Akins, Hollis B. • Brinch, Malte • Berman, Edward • Casey, Caitlin M. • Drakos, Nicole E. • Faisst, Andreas L. • Franco, Maximilien • Fung, Leo W. H. • Gozaliasl, Ghassem • He, Qiuhan • Hatamnia, Hossein • Huff, Eric • Hogg, Natalie B. • Ilbert, Olivier • Kartaltepe, Jeyhan S. • Koekemoer, Anton M. • Jin, Shouwen • Lambrides, Erini • Leauthaud, Alexie • Lentz, Zane D. • Liu, Daizhong • Mahler, Guillaume • Maraston, Claudia • Martin, Crystal L. • McCleary, Jacqueline • Nightingale, James • Mobasher, Bahram • Paquereau, Louise • Pires, Sandrine • Robertson, Brant E. • Sanders, David B. • Scarlata, Claudia • Shuntov, Marko • Toni, Greta • von Wietersheim-Kramsta, Maximilian • Weaver, John R.

Abstract • Ordinary matter—including particles such as protons and neutrons—accounts for only about one-sixth of all matter in the Universe. The rest is dark matter, which does not emit or absorb light but plays a fundamental role in galaxy and structure evolution. Because it interacts only through gravity, one of the most direct probes is weak gravitational lensing: the deflection of light from distant galaxies by intervening mass. Here we present an extremely detailed, wide-area weak-lensing mass map covering 0.77° × 0.70°, using high-resolution imaging from the James Webb Space Telescope as part of the COSMOS-Web survey. By measuring the shapes of 129 galaxies per square arcminute—many independently in the F115W and F150W bands—we achieve an angular resolution of 1.00 ±0.0 1^'. Our map has more than twice the resolution of earlier Hubble Space Telescope maps, revealing how dark and luminous matter co-evolve across filaments, clusters and underdensities. It traces mass features out to z ≈ 2, including the most distant structure at z ≈ 1.1. The sensitivity to high-redshift lensing constrains galaxy environments at the peak of cosmic star formation and sets a high-resolution benchmark for testing theories about the nature of dark matter and the formation of large-scale cosmic structure.

Links

• PREPRINT http://arxiv.org/abs/2601.17239
• DATA http://irsa.ipac.caltech.edu/data/COSMOS/
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2026NatAs..10..573S
• DATA https://exchg.calet.org/cosmosweb-public/DR0.5/
• DATA https://irsa.ipac.caltech.edu/data/COSMOS/
• DATA https://irsa.ipac.caltech.edu/data/COSMOS/gator_docs/cosmos_chandraxid_colDescriptions.html
• ELECTR https://doi.org/10.1038%2Fs41550-025-02763-9