A strange, never-before-seen glow in the halo of our galaxy may be the strongest dark-matter breadcrumb yet.

A new analysis of 15 years’ worth of data from the Fermi Gamma-Ray Space Telescope reveals a glow of unusually high-energy gamma rays that cannot easily be attributed to any known source.

According to astronomer Tomonori Totani of the University of Tokyo in Japan, it may be the radiation produced when hypothetical dark matter particles collide and wipe out one another.