Hidden dark-matter force may curb growth of cosmic structures, study finds

A new theoretical analysis suggests that an additional attractive force between dark-matter particles can paradoxically slow the formation of large-scale structures in the Universe.

A team of theorists examined scenarios where dark-matter particles experience a supplementary attractive interaction, often termed a “dark force.” Their calculations show that although this force enhances particle clustering, it also leads to a progressive loss of effective mass during cosmic expansion, reducing the particles' gravitational influence. The combined outcome is a slowdown in the development of large-scale cosmic structures, contrary to initial expectations.

The findings, appearing in the Journal of Cosmology and Astroparticle Physics, could affect models that invoke similar forces to explain tensions in DESI data and cosmic-microwave-background measurements. The authors argue that future high-precision surveys will be essential to test whether such hidden interactions exist. Zachary Weiner of the Perimeter Institute highlighted the subtlety of the universe’s behavior and the need for continued scrutiny of dark-matter properties.