Scientists have revealed they may be closer than ever to confirming the existence of dark matter, the mysterious substance thought to make up more than a quarter of the universe, following new research into a strange gamma-ray glow near the center of the Milky Way.
Dark matter, which does not absorb, reflect or emit light, is estimated to make up about 27 percent of the universe. In contrast, ordinary matter—everything visible, from stars and planets to people and objects—makes up just five percent, while the rest is made up of dark energy, an even more mysterious force believed to be driving the expansion of the universe.
Despite decades of searching, scientists have yet to detect dark matter directly. Its presence has only been inferred from its gravitational influence on galaxies and cosmic structures. However, new findings from the Fermi Gamma-ray Space Telescope may bring researchers a little closer.
The telescope observed an excess of gamma rays in the inner 7,000 light-years of the Milky Way, a region about 26,000 light-years from Earth. Scientists say this glow could come from the collision of dark matter particles or millisecond pulsars, which are rapidly spinning neutron stars that emit high-energy radiation.
A recent study published in Physical Review Letters suggests that both explanations are equally likely. The team’s simulations show that dark matter annihilation could produce a gamma-ray signal identical to the one detected by Fermi.
“Understanding the nature of dark matter is one of the greatest challenges in physics,” said Professor Joseph Silk, a cosmologist at Johns Hopkins University and the Institute of Astrophysics in Paris. “Our key result is that dark matter fits the gamma-ray data as well as the rival neutron star hypothesis. We have increased the probability that dark matter has been detected indirectly.”
Researchers hope that the Cherenkov Telescope Array Observatory, under construction in Chile and expected to begin operating in 2026, will help resolve the debate by distinguishing between the two possible sources of gamma rays.
Lead author Moorits Mihkel Muru of the University of Tartu in Estonia explained that dark matter can only be detected indirectly:
“Since dark matter does not emit or block light, we can only observe its effects on visible matter. No experiments have yet detected dark matter particles directly.”
Gamma rays, the most energetic form of light, are key to this search because if dark matter particles annihilate when they collide, these interactions are expected to produce gamma rays as a byproduct.
Scientists believe that the Milky Way itself formed when a vast cloud of dark matter and ordinary matter collapsed under gravity, pulling material toward its center, where this mysterious glow now shines.
(Reuters)
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