Mysterious light at the center of the galaxy could be a trace of "dark matter"

NEWS CENTER

Created: October 23, 2025 10:53

"Dark matter dominates the universe and holds galaxies together. We're constantly searching for new ways to detect it. This excess gamma light at the center of the Milky Way could be our first clue," said one of the researchers, Professor Joseph Silk, an astrophysicist at Johns Hopkins University.

THE MYSTERY UNSOLVED SINCE 2009

Scientists first noticed this mysterious glow in data from NASA 's Fermi Gamma-ray Space Telescope in 2009. The source of this glow, called the "Galactic Center GeV Excess (GCE)," has been a matter of debate ever since.

There are two main candidates: First, dark matter, the source of the unseen mass in the universe. Theoretically, when these particles, called "weakly interacting massive particles" (WIMPs), collide, they annihilate each other, producing bursts of energy that emit gamma rays.

Another possibility is millisecond pulsars: the extremely dense remnants of massive stellar cores that collapsed in supernova explosions, spinning hundreds of times per second. These pulsars emit radio waves, X-rays, and gamma rays as they spin.

'BOX-SHAPED' GLITTER MAY REFER TO DARK MATTER

The bulge of old stars at the center of the Milky Way has an "X"-shaped structure. This corresponds to the distribution of pulsars. However, according to dark matter theory, the galactic halo should generally be spherical. If the glow is box-shaped, it was thought to be the work of pulsars, and if it is spherical, it was thought to be the work of dark matter. However, new research has shown that this distinction is not as clear-cut as previously thought.

A team led by Moorits Mihkel Muru of the Leibniz Institute for Astrophysics in Germany used supercomputers to simulate the evolution of galaxies similar to the Milky Way over billions of years. They found that the Milky Way's dark matter halo has flattened somewhat over time due to galaxy mergers. This means the dark matter glow may also appear box-shaped.

This revealed that the box-shaped nature of the glow is not limited to pulsars but can also be explained by dark matter.

A SMALL ADVANTAGE TO DARK MATTER

According to the researchers, both scenarios are "equally likely" in terms of the shape, intensity and spectrum of the gamma flare, but the dark matter explanation is a step ahead due to the lack of pulsar numbers.

However, the data isn't entirely conclusive. Some observations suggest the glow has a slightly "speckled" structure, similar to point sources (pulsars). Dark matter , however, would produce a more uniform glow. Scientists believe these small-scale differences will become clearer with future observations.

ANSWERS WILL COME FROM NEW TELESCOPES IN THE SKY

The upcoming Cherenkov Telescope Array (CTA) and the Southern Wide-Field Gamma-Ray Observatory will play a key role in unraveling this mystery. "The new data could confirm a theory or make things even more mysterious," Silk says. "Either way, we'll get a little closer to the universe's darkest secret."