NASA’s Fermi Gamma-ray Space Telescope may have detected the first direct evidence for dark matter, according to a University of Tokyo astronomer.
The existence of dark matter is an essential component in our understanding of the Standard Model of Cosmology. Yet because it emits no light and does not interact electromagnetically with other matter, it remains extraordinarily difficult to detect.
Now, Professor Tomonori Totani with the University of Tokyo’s Department of Astronomy reports new evidence for the existence of dark matter in gamma-ray observations, as detailed in the Journal of Cosmology and Astroparticle Physics.
The Nature of Dark Matter
Determining what dark matter actually is has long challenged scientists. Its gravitational effects—most notably the ability to hold galaxies together—are well documented. But because the particles neither absorb, reflect, nor emit light, they cannot be directly imaged, and no definitive detection has yet been made.
One leading candidate for dark matter is a class of particles known as weakly interacting massive particles (WIMPs). Heavier than protons yet interacting only faintly with other matter, WIMPs are believed to annihilate each other when they collide, producing gamma-ray photons in the process.
This predicted gamma-ray signature has driven decades of searches in regions thought to be dense with dark matter, such as the Milky Way’s galactic center. Now, Totani says his analysis of data from the Fermi Gamma-ray Space Telescope may have finally revealed those long-anticipated signals.
Gamma Ray Results
“We detected gamma rays with a photon energy of 20 gigaelectronvolts (or 20 billion electronvolts, an extremely large amount of energy) extending in a halolike structure toward the center of the Milky Way galaxy,” Professor Totani said in a statement. The gamma-ray emission component closely matches the shape expected from the dark matter halo.”
Totani’s analysis indicates that the gamma-ray intensity corresponds to particles roughly 500 times the mass of a proton—a value consistent with expectations for WIMP annihilation. Other natural gamma-ray sources, such as radioactive decay or particle collisions, do not match the observed measurements collected by Fermi.
Totani argues this strengthens the case that the signal originates from dark matter.
“If this is correct, to the extent of my knowledge, it would mark the first time humanity has ‘seen’ dark matter,” Totani said. “And it turns out that dark matter is a new particle not included in the current standard model of particle physics. This signifies a major development in astronomy and physics.”
Seeking Confirmation
Further analysis by independent research groups will be crucial to confirm Totani’s interpretation. Beyond reinforcing the measurements themselves, scientists must rule out alternative astrophysical explanations for the gamma-ray excess at the Milky Way’s center.
Additional observations in other regions may also prove useful. Dwarf galaxies orbiting within the Milky Way’s halo are thought to contain significant amounts of dark matter. Detecting a similar gamma-ray signature in those galaxies would provide strong corroboration.
Endorsing the need for continued investigation, Totani concluded, “This may be achieved once more data is accumulated, and if so, it would provide even stronger evidence that the gamma rays originate from dark matter.”
The paper, “20 GeV Halo-like Excess of the Galactic Diffuse Emission and Implications for Dark Matter Annihilation,” was accepted for publication in the November 26, 2025, edition of the Journal of Cosmology and Astroparticle Physics.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.