Overview
- University of Tokyo astronomer Tomonori Totani reports a halo-like excess of roughly 20 GeV gamma rays toward the Milky Way using Fermi LAT observations spanning about 15 years.
- The measured spectrum and sky shape match long-standing WIMP annihilation predictions, implying particles about 500 times the proton mass with an annihilation rate consistent with theory.
- The study filters out the Galactic plane and the inner roughly 10 degrees around the center to reduce contamination from known gamma-ray sources and backgrounds.
- Outside experts describe the claim as intriguing yet unproven, noting prior analyses of the same dataset did not see this excess and that astrophysical processes or modeling choices could mimic the signal.
- Verification now hinges on independent reanalyses and on detecting the same 20 GeV feature in dark-matter–dominated dwarf galaxies, with further observations expected from Fermi and the upcoming CTAO.