Dark matter map assembled by scientists is the most detailed yet

A study published Jan. 26 in Nature Astronomy uses James Webb Space Telescope observations to produce the highest-resolution dark matter map to date, covering the COSMOS field and tracing about 800,000 galaxies through weak gravitational lensing.

Scientists have produced the highest-resolution map of dark matter so far, published Jan. 26 in Nature Astronomy. The map was built from James Webb Space Telescope infrared observations of the COSMOS field and uses weak gravitational lensing to infer the distribution of invisible mass. Webb observations totaled about 255 hours and revealed nearly 800,000 galaxies across a small patch of sky roughly 2.5 times the area of the full moon. Researchers say the map reinforces the view that dark matter formed a gravitational scaffolding that guided ordinary matter into galaxies. Key findings: - The study was published Jan. 26 in Nature Astronomy and is based on James Webb Space Telescope infrared imaging. - Webb observed the COSMOS field for about 255 hours and identified nearly 800,000 galaxies in an area about 2.5 times the full moon. - The dark matter distribution was inferred using weak gravitational lensing, measuring subtle distortions in background galaxy shapes. - The map shows filamentary structure consistent with a "cosmic web" where galaxies align along dark matter threads. - The article notes complementary and forthcoming large surveys from ESA's Euclid (launched 2023), NASA's Nancy Grace Roman Space Telescope (described as expected to launch this fall), and the Vera C. Rubin Observatory. - Researchers report they are working on a three-dimensional version of the Webb dark matter map to combine with wider surveys. Summary: The new Webb map provides a higher-resolution view of dark matter in a well-studied patch of sky and supports the picture of dark matter as a gravitational framework for galaxy formation. Researchers plan a three-dimensional map and intend to combine Webb data with larger surveys from other observatories to study how dark matter and galaxies relate and to investigate properties of dark matter such as whether it behaves as "cold" or "warm".