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Milky Way Simulations Revive Dark-Matter Case for Galactic Center Gamma-Ray Excess

Higher-resolution CTA data could deliver a decisive test of the signal's origin.

A render of the Cherenkov Telescope Array.
Image
Image
A bright band of diffuse gamma ray glow along the map's center, which marks the central plane of the Milky Way galaxy, is seen in an undated image based on five years of data from NASA's Fermi Gamma-ray Space Telescope. NASA/DOE/Fermi LAT Collaboration/Handout via REUTERS

Overview

  • A peer-reviewed Physical Review Letters study published Oct. 16 reports that dark-matter annihilation reproduces the Fermi-LAT excess at least as well as the millisecond-pulsar explanation.
  • Supercomputer models that include the Milky Way's formation history yield a flattened dark-matter distribution that matches the observed gamma-ray morphology.
  • Researchers say pulsars remain a viable source, though fitting the data would require many more unresolved millisecond pulsars than have been detected.
  • The excess occupies the inner roughly 7,000 light-years of the galaxy mapped since 2009, consistent with gamma rays expected if certain dark-matter particles annihilate.
  • The team is preparing spectral and dwarf-galaxy predictions, with the Cherenkov Telescope Array targeted for around 2026 to distinguish between the competing origins.