A signal coming from the centre of the Milky Way could be the best sign of dark matter yet.
The gamma rays were detected by scientists looking at publicly available data from Nasa's Fermi Gamma-ray Space Telescope.
What dark matter is actually made of is one of the biggest questions facing physics today.
WIMPs, or Weakly Interacting Massive Particles, are a leading candidate. There are several different types of (theoretical) WIMP, and many produce gamma rays that the Fermi experiment's telescope would be able to detect.
What we do know is that dark matter makes up 27% of the total mass and energy of the universe. Normal matter makes up just 5% of the total universe.