In a potential scientific breakthrough, researchers may have directly 'seen' dark matter for the first time, using data collected by NASA's Fermi Gamma-ray Space Telescope. If confirmed, the discovery could mark a turning point in the decades-long effort to uncover the nature of this invisible substance that dominates most of the universe's mass.
Scientists say they may have finally seen signs of dark matter through a gamma-ray signal near the center of the Milky Way.
The detection centers on a specific type of high-energy radiation. A team led by Tomonori Totani from the University of Tokyo reported observing gamma rays with an energy of 20 billion electronvolts, forming a halo-like pattern around the galactic center.
This structure closely aligns with what theoretical models predict for a dark matter halo. The findings also match the expected energy profile of WIMPs, or Weakly Interacting Massive Particles, which are considered strong candidates for dark matter.
Totani said the signal could represent the first visual evidence of dark matter, a particle that lies outside the Standard Model of particle physics. He noted that no known natural sources explain the specific pattern and energy of the gamma rays seen by the Fermi telescope.
The theory behind dark matter dates back to 1933, when astronomer Fritz Zwicky noticed that the Coma Cluster of galaxies lacked enough visible mass to stay gravitationally bound.
In the 1970s, Vera Rubin and her colleagues found that spiral galaxies rotated in a way that implied most of their mass was not visible. These early findings pointed to a hidden substance exerting gravitational effects but escaping direct observation.
Scientists estimate that dark matter outweighs ordinary matter by five to one. That means visible matter, including stars, planets and all living things, accounts for only about 15 percent of the universe's total matter. The rest is believed to be dark matter, which does not absorb, reflect or emit light, making it essentially invisible.
The idea that dark matter particles might annihilate each other and release gamma rays has long been considered. If WIMPs exist and collide, they are expected to produce high-energy photons.
Totani's team focused on the galactic center, a region thought to be dense with dark matter, and found gamma rays consistent with that theory.
While Totani believes the findings strongly suggest dark matter interactions, he acknowledged that more data is needed.
He said additional evidence could help confirm that the signal indeed originates from dark matter. The study was published on November 25 in the Journal of Cosmology and Astroparticle Physics.