Led by Dr. Moorits Muru, with Dr. Noam Libeskind and Dr. Stefan Gottlober from the Leibniz Institute for Astrophysics Potsdam (AIP), in collaboration with Professor Yehuda Hoffman of the Hebrew University of Jerusalem and Professor Joseph Silk of Oxford University, the research was published in Physical Review Letters. Using advanced cosmological simulations, the team demonstrated that dark matter - the invisible substance believed to make up most of the universe - could still account for the so-called "Galactic Center Excess" first detected by NASA's Fermi Gamma-ray Space Telescope.
For over a decade, scientists have been divided over the source of this unexpected gamma-ray concentration. Initial models proposed that the radiation resulted from dark matter particles colliding and annihilating each other. However, subsequent data showed that the spatial pattern of the rays did not neatly match standard dark matter profiles, leading many to favor an alternative explanation involving millisecond pulsars - fast-spinning neutron stars clustered near the galactic core.
The new study revisits that assumption using the Hestia suite of high-resolution simulations, which model galaxies in environments similar to our own cosmic neighborhood. By reconstructing how the Milky Way formed - including ancient mergers and gravitational turbulence - the researchers found that such dynamic events could have distorted the distribution of dark matter in the galactic center.
Their results indicate a more complex, non-spherical dark matter structure capable of producing the observed gamma-ray spread without requiring a dense pulsar population.
"The Milky Way's history of collisions and growth leaves clear fingerprints on how dark matter is arranged at its core," the researchers said. "When we account for that, the gamma-ray signal looks a lot more like something dark matter could explain."
While the findings do not end the debate, they restore dark matter as a serious contender. Upcoming observatories like the Cherenkov Telescope Array, designed to probe even higher-energy gamma rays, may help distinguish whether the excess originates from dark matter interactions or other astrophysical processes.
"This study gives us a fresh way to interpret one of the most intriguing signals in the sky," the team added. "Either we'll confirm that dark matter leaves an observable trace - or we'll learn something entirely new about the Milky Way itself."
Research Report:Fermi-LAT Galactic Center Excess morphology of dark matter in simulations of the Milky Way galaxy
Related Links
The Hebrew University of Jerusalem
Stellar Chemistry, The Universe And All Within It
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