RELATED: 'Axion-like Particles' Probably Not a Dark Matter Answer
Astrophysicists know that galaxies emit gamma-rays, but to have such a powerful gamma-ray signal coming from the center of Andromeda means something strange is going on.
"We expect dark matter to accumulate in the innermost regions of the Milky Way and other galaxies, which is why finding such a compact signal is very exciting," said astrophysicist Pierrick Martin, of the National Center for Scientific Research and the Research Institute in Astrophysics and Planetology in Toulouse, France.
It is thought that when dark matter particles, such as hypothesized weakly-interacting massive particles (or WIMPS), collide, they annihilate, releasing a sudden burst in energy. This energy is in the form of gamma-rays, so where Fermi sees an intense gamma-ray emitting region, it could indicate the location of a dense cloud of dark matter.
There could be another explanation, however. The researchers point out that a dense accumulation of pulsars could also generate an intense gamma-ray signal, but Andromeda is 2.5 million light-years away, so there's no way to resolve individual pulsar sources of gamma-rays.