No one knows exactly what dark matter is, but scientists know that it is there because of the gravitational influence it exerts on objects. One of the leading theories suggests that dark matter particles are Weakly Interactive Massive Particles (WIMPs) and that when these particles meet it results in high energy gamma rays.

If that is true then in areas where there is a lot of dark matter there should be detectible gamma rays. The problem is that gamma rays are also emitted by black holes and pulsars which makes it difficult to separate possible dark-matter gamma rays from the other sources.

Now, a team of researchers has noticed a strong source of gamma rays coming from a newly discovered dwarf galaxy that orbits the milky way. At this point they can’t be certain about the source of the gamma rays but it’s possible that they signal a strong concentration of dark matter at the core of the galaxy.

“Something in the direction of this dwarf galaxy is emitting gamma rays. There’s no conventional reason this galaxy should be giving off gamma rays, so it’s potentially a signal for dark matter,” said Alex Geringer-Sameth in a statement.

Geringer-Sameth is a postdoctoral research associate in Carnegie Mellom University’s Department of Physics and the lead author of a paper submitted to the journal Physical Review Letters and posted on arXiv.

The galaxy, Reticulum 2, was discovered in the Dark Energy Survey “an experiment that maps the southern sky to understand the accelerated expansion of the universe.” Reticulum 2 is 98,000 light years from Earth which makes it one of the closest dwarf galaxies discovered to date.

The presence of gamma rays emanating from the galaxy was confirmed using data from NASA’s Fermi Gamma-ray Space Telescope.

Over the last few years, the researchers have been developing a technique designed to search for weak signals in the gamma ray data that could point to sources of dark matter.

The discovery of Reticulum 2 provided exactly the type of system they were looking for.

“There did seem to be an excess of gamma rays, above what you would expect from normal background processes, coming from the direction of this galaxy. Given the way that we think we understand how gamma rays are generated in this region of the sky, it doesn’t seem that those processes can explain this signal,” said Geringer-Sameth.

Dark matter is believed to make up about 80 percent of the universe. Because it has such a strong influence, being able to identify and study dark matter could greatly expand our understanding of the universe.

“The gravitational detection of dark matter tells you very little about the particle behavior of the dark matter. But now we may have a non-gravitational detection that shows dark matter behaving like a particle, which is a holy grail of sorts,” said Matthew Walker, assistant professor of physics and a member of Carnegie Mellon University’s McWilliams Center for Cosmology.

The researchers note that while the possibility is exciting, that there is much more research to be done before dark matter is confirmed.