JWST Unveils Most Detailed Dark Matter Map

Astronomers have unveiled the most detailed map to date of dark matter's distribution across a vast region of the universe, using observations from NASA's James Webb Space Telescope. The map, published Monday in the journal Nature Astronomy, covers an area in the constellation Sextans roughly 2.5 times the size of the full moon and reveals the invisible substance's role in shaping cosmic structures over billions of years.

Lead author Diana Scognamiglio, a postdoctoral researcher at NASA's Jet Propulsion Laboratory, and her international team analyzed images from the COSMOS-Web survey, which peered into this sky patch for about 255 hours. The telescope identified nearly 800,000 galaxies, some visible for the first time, spanning the past 10 billion years of cosmic history. By measuring subtle distortions in the shapes of these distant galaxies—caused by dark matter's gravitational pull along the light's path—the researchers reconstructed the locations of unseen mass. This technique, known as weak gravitational lensing, allowed them to trace dark matter's concentrations with twice the resolution of previous maps created using the Hubble Space Telescope.