For decades, astronomers have been puzzled by a faint but powerful glow of gamma rays shining from the center of our Milky Way galaxy. Now, researchers from Johns Hopkins University believe this strange light could be our first real clue to uncovering one of the universe’s greatest mysteries—dark matter, the invisible substance thought to make up most of the cosmos.
In a new study published in *Physical Review Letters*, the team found that two competing explanations for the glow are equally possible: it could come from dark matter particles colliding and releasing energy, or from clusters of old, rapidly spinning neutron stars known as millisecond pulsars. If the dark matter theory turns out to be true, it would be the first direct evidence of its existence.
“Dark matter dominates the universe and holds galaxies together,” said co-author Joseph Silk, a professor of physics and astronomy at Johns Hopkins and a researcher at the Institut d’Astrophysique de Paris and Sorbonne University. “Gamma rays, and specifically the excess light we’re observing at the center of our galaxy, could be our first clue.”
To explore the mystery, the team used supercomputers to create detailed maps of where dark matter should be found in the Milky Way. For the first time, they incorporated the galaxy’s formation history into their models.
Billions of years ago, the Milky Way formed from many smaller galaxies that merged together. Each of those small systems contained dark matter, which gradually sank toward the galactic center as gravity pulled it inward. Over time, these dense regions could have led to frequent collisions between dark matter particles—possibly generating the gamma rays seen today.
When the researchers compared their dark matter simulation maps to real data from NASA’s Fermi Gamma-ray Space Telescope, the two matched closely. This agreement adds weight to the idea that dark matter collisions might be responsible for the mysterious light.
However, the researchers caution that it’s not yet definitive proof. The alternative theory—that millisecond pulsars are producing the gamma rays—also fits the data. But for that explanation to work, scientists would have to assume there are far more of these tiny, fast-spinning stars than have ever been observed.
To finally solve the puzzle, astronomers are looking to the upcoming Cherenkov Telescope Array, a powerful new observatory designed to detect high-energy gamma rays with much greater precision. The Johns Hopkins team also plans new experiments to test whether the Milky Way’s gamma rays carry the energy signatures of pulsars or of dark matter collisions.
“A clean signal would be a smoking gun,” said Silk. “Either way, the result will reshape our understanding of what’s really shining at the heart of our galaxy.”
https://knowridge.com/2025/10/mysterious-galactic-glow-may-be-the-first-sign-of-dark-matter/