For decades, astronomers have been puzzled by a mysterious glow of gamma rays emanating from near the center of the Milky Way. Two theories have emerged: either the light was the result of dark matter particles colliding, or it’s coming from rapidly spinning neutron stars — the extremely dense remains of exploded stars — called pulsars.
Now, a new paper published in the journal Physical Review Letters might not have a satisfying answer — it argues that both theories are equally likely — but it does raise the stakes: if the first possibility turns out to be correct, it could be the first-ever concrete evidence that dark matter, the mysterious stuff that is believed to make up more than 26 percent of the universe, actually exists.
“Dark matter dominates the universe and holds galaxies together,” said coauthor and Johns Hopkins astronomy professor Joseph Silk in a statement. “It’s extremely consequential and we’re desperately thinking all the time of ideas as to how we could detect it.”
“Gamma rays, and specifically the excess light we’re observing at the center of our galaxy, could be our first clue,” he added.
While taking into consideration how the Milky Way formed, Silk and his international colleagues created a dark matter map to identify where it should be located.
Scientists believe that billions of years ago, smaller galaxy-like systems of dark matter clumped together at the center of what is now the Milky Way, causing collisions between the clumps to increase.
By simulating these collisions, the researchers found that their dark matter map overlapped with existing gamma ray maps, produced with data from NASA’s Fermi Gamma-ray Space Telescope.
While it’s an intriguing match, scientists are still far from concluding that the glow at the heart of our galaxy is the result of dark matter. It’s quite possible that pulsars are the culprit.
Fortunately, an upcoming gamma ray telescope, dubbed the Cherenkov Telescope Array Observatory, could clear things up. The multinational project will be comprised of 60 telescopes across two locations, one on the Spanish island of La Palma and one in the Atacama Desert in Chile, to probe galactic sources of gamma rays.
With these higher-resolution images, researchers are hoping to hone in on the source of the mysterious glow at the center of our galaxy that has puzzled astronomers for decades.
“A clean signal would be a smoking gun, in my opinion,” Silk said in the statement.
For now, Silk and his colleagues are looking to probe other neighboring dwarf galaxies for dark matter and whether its distribution matches existing gamma ray maps.
“It’s possible we will see the new data and confirm one theory over the other,” Silk concluded. “Or maybe we’ll find nothing, in which case it’ll be an even greater mystery to resolve.”
More on dark matter: Astronomers Detect Mysterious Dark Object in Distant Galaxy
