The centre of our Galaxy is a mysterious place. For decades, astronomers have puzzled over the strange glow emanating from the Milky Way’s core.
Made up of gamma rays, its origins remain uncertain.
The two prevailing theories are that the source of the rays is either dying stars called millisecond pulsars (rapidly rotating neutron stars) or, more excitingly, colliding dark matter particles.
Now, new research suggests that the chances of it being dark matter are higher than previously thought, although it still puts the chances of either theory being correct at 50/50.
If confirmed, this would be the first concrete evidence that this elusive substance exists.
More on dark matter
"Dark matter dominates the Universe and holds galaxies together. It’s extremely consequential and we’re desperately thinking all the time of ideas as to how we could detect it," says study co-author Joseph Silk, a professor of physics and astronomy at Johns Hopkins University.
"Gamma rays, and specifically the excess light we’re observing at the centre of our Galaxy, could be our first clue."
To test the idea, the researchers fed data on the Milky Way’s formation into a supercomputer.
This then calculated a map of where dark matter is likely to have ended up as our Galaxy formed.
Their simulated maps closely matched actual gamma-ray observations by the Fermi Gamma-ray Space Telescope.
Although this isn’t definitive proof, the similarities certainty add weight to the dark matter theory.
Add to this the fact that there haven’t been enough millisecond pulsars observed to explain the mysterious glow and the amount of gamma rays detected, and you can see why researchers are excited.
The argument could be settled with the construction of a huge new gamma-ray telescope called the Cherenkov Telescope Array.
Planned for 2030, this will allow the energies of the gamma rays to be measured.
If they are high-energy rays, then that would point to pulsars; if they are low-energy rays, that would indicate dark matter collisions.
"A clean signal would be a smoking gun, in my opinion," says Silk.
"It’s possible we will see the new data and confirm one theory over the other. Or maybe we’ll find nothing, in which case it’ll be an even greater mystery to resolve."
