Dark matter may be lighting up the heart of the Milky Way

The new study has breathed fresh life into one of astrophysics' most persistent debates: what is causing the powerful gamma-ray glow at the center of our galaxy?

Led by Dr. Moorits Muru, with Dr. Noam Libeskind and Dr. Stefan Gottlöber of the Leibniz Institute for Astrophysics Potsdam (AIP), in collaboration with Professor Yehuda Hoffman of the Hebrew University of Jerusalem's Racah Institute of Physics and Professor Joseph Silk of Oxford University, the research appears in Physical Review Letters. Their work uses advanced cosmological simulations to test whether dark matter -- the invisible material thought to make up most of the universe -- can still account for the surplus of high-energy radiation first spotted by NASA's Fermi Gamma-ray Space Telescope.

Revisiting the Galactic Center Excess

For more than a decade, scientists have wrestled with the so-called "Galactic Center Excess," an unexpected surge of gamma rays streaming from the Milky Way's heart. Early on, researchers suspected that dark matter particles migh t be colliding and annihilating each other, creating intense bursts of radiation. However, the observed pattern of gamma rays didn't quite fit the expected shape of dark matter distributions. This discrepancy led many to favor another explanation: ancient, fast-spinning neutron stars known as millisecond pulsars.

To test the possibilities, the team turned to Hestia, a series of high-resolution simulations designed to model galaxies like the Milky Way within realistic cosmic environments. By retracing the galaxy's violent mergers and chaotic beginnings, the researchers found that these ancient events could have significantly altered the shape and density of dark matter in its core.

Their results reveal a far more intricate, nonspherical dark matter structure than earlier models predicted -- one that naturally reproduces the spread of gamma rays without the need to invoke large numbers of pulsars.

The Milky Way's Chaotic Past Leaves a Mark

"The Milky Way's history of collisions and growth leaves clear fingerprints on how dark matter is arranged at its core," the researchers explained. "When we account for that, the gamma-ray signal looks a lot more like something dark matter could explain."

Although the study doesn't end the debate, it reestablishes dark matter as a leading explanation for one of modern astronomy's most intriguing phenomena.

Future observatories such as the Cherenkov Telescope Array, capable of detecting even higher-energy gamma rays, will provide sharper tests of these competing theories. These instruments could confirm whether the glow truly comes from dark matter or whether another cosmic process is responsible.

"This study gives us a fresh way to interpret one of the most intriguing signals in the sky," the team said. "Either we'll confirm that dark matter leaves an observable trace -- or we'll learn something entirely new about the Milky Way itself."