New research indicates that the distribution of dark matter in the Milky Way is not what scientists previously thought. This study suggests that dark matter annihilation may account for the observed gamma ray excess in the galaxy’s center. The findings, published on October 19, 2025, in the journal Physical Review Letters, highlight a significant advancement in understanding dark matter’s role in cosmic phenomena.
High-resolution simulations conducted by researchers at the Leibniz Institute for Astrophysics Potsdam, in collaboration with the Hebrew University and Johns Hopkins University, reveal that the dark matter distribution in the inner Milky Way is flattened and asymmetrical, rather than spherical. This new model supports the hypothesis that the gamma ray excess observed is a result of dark matter particles colliding and annihilating each other.
Scientists have long speculated that dark matter annihilation could be responsible for the gamma rays detected by the FERMI space telescope. The telescope recorded an unexpected number of gamma rays, the universe’s most energetic light. Initially, two primary theories emerged: one suggested that these gamma rays stemmed from ancient millisecond pulsars, while the other proposed that they originated from dark matter particles.
Noam Libeskind, a researcher at the Leibniz Institute, noted the initial confusion among astronomers regarding the gamma ray excess. “When the FERMI space telescope pointed to the galactic center, the results were startling,” he stated. “Astronomers around the world were puzzled, and competing theories started pouring in.”
The recent study indicates that dark matter does not radiate uniformly from the Galactic Center. Instead, it is organized in a manner similar to stars. This revelation implies that dark matter could equally account for the gamma rays as millisecond pulsars might.
Lead author Moorits Muru emphasized the significance of the findings, stating, “We analyzed simulations of the Milky Way and its dark matter halo and found that the flattening of this region is sufficient to explain the gamma ray excess as being due to dark matter particles self-annihilating.” Muru added that these calculations encourage further exploration in the search for dark matter particles capable of self-annihilation.
The Milky Way is situated within a dark matter halo, a spherical region filled with dark matter. However, the degree to which this halo is aspherical or ellipsoidal has not been thoroughly appreciated until now. The research demonstrates that the unique shape of the dark matter halo around the Milky Way plays a crucial role in the distribution and potential annihilation of dark matter particles.
In conclusion, this groundbreaking study not only advances the understanding of dark matter distribution in our galaxy but also reinforces the idea that dark matter annihilation may explain the gamma ray excess observed from the center of the Milky Way. As researchers continue to investigate these enigmatic particles, the findings may bring humanity closer to unraveling the mysteries of the universe.
