News release

From: Springer Nature

A detailed map of the Universe’s dark matter

An ultra-high-resolution map of mass in the Universe, revealing how dark matter has shaped the growth of galaxies over the past 10 billion years, is published in Nature Astronomy. The map has more than twice the resolution of its predecessor and extends to earlier periods in the Universe’s evolution, providing a benchmark for tests of the nature of dark matter and models of galaxy environments during the peak period of cosmic star formation, about 8–11 billion years ago.
Dark matter, which makes up around 85% of the Universe’s matter, is difficult to detect because it does not emit or absorb light and is therefore invisible to conventional telescopes. Its gravity, however, affects the paths of light from distant galaxies. By measuring the slight distortions in the shapes of a very large number of distant galaxies, scientists can trace how the intervening mass is distributed, regardless of its nature. Comparison with known luminous structures then reveals where the dark matter must lie. Previous maps, based on the Hubble Space Telescope and other facilities, have lacked either resolution, sensitivity or area, limiting the view to only the largest and most massive structures in the cosmic web.

Diana Scognamiglio and colleagues used imaging from the James Webb Space Telescope to measure the shapes of around 250,000 galaxies and reconstruct the most detailed mass map to date of any contiguous region of the Universe. The map reveals massive galaxy clusters as well as networks of dark filamentary bridges (strands of dark matter, along which gas and galaxies are distributed, forming the skeletal structure of the Universe) and low-mass galaxy groups that are otherwise too faint or too distant to be seen with conventional telescopes. These structures appear consistent with the leading cosmological model, which predicts that galaxies form at dense nodes between the dark matter filaments that thread or span the Universe.

The authors suggest that these maps will be a valuable resource for studies of galaxy evolution and the growth of cosmic structure.