Researchers studying a mysterious gamma-ray glow near the center of the Milky Way may be one step closer to confirming the existence of dark matter, the invisible material thought to make up around 27% of the universe.
Unlike ordinary matter, which accounts for just 5% of the universe and can be seen in various wavelengths, dark matter neither emits nor reflects light. Its presence has been inferred through gravitational effects on galaxies, but it has never been detected directly.
A recent study, published in Physical Review Letters, analyzed gamma rays captured by the Fermi Gamma-ray Space Telescope from a region roughly 7,000 light-years wide and 26,000 light-years from Earth. The research suggests that these rays could be produced by colliding dark matter particles, or by millisecond pulsars, rapidly spinning neutron stars known to emit gamma rays.
The study’s simulations found both explanations equally likely. “We’ve increased the odds that dark matter has been indirectly detected,” said co-author Joseph Silk, a cosmologist at Johns Hopkins University and the Sorbonne.
Scientists hope the upcoming Cherenkov Telescope Array in Chile, expected to go online by 2026, will help determine which source is responsible. Until then, the glow remains a tantalizing clue in one of physics’ most enduring mysteries.