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Individual particles of dark matter are hard to see — there are no confirmed detections of a single one. But get two particles together and it’s a different story. They may annihilate each other, producing a gamma ray — the most powerful form of energy. In fact, a gamma-ray telescope in space may be seeing the glow of many of these interactions in the center of the Milky Way galaxy.
Dark matter produces no detectable energy. But we know it’s there because it exerts a gravitational pull on the visible matter around it. By measuring the gravitational effects, scientists have concluded that dark matter accounts for about five-sixths of all the matter in the universe.
The leading theory says dark matter consists of heavy particles known as WIMPs. They almost never interact with normal matter, which makes them almost impossible to detect. Several experiments have found hints of them, but no confirmed discoveries.
But the Fermi space telescope has found a gamma-ray glow that extends thousands of light-years from the center of the galaxy. The glow is consistent with models of annihilating dark matter. There should be more dark matter in the center of the galaxy than elsewhere, making such collisions more likely. And no other known source can explain the glow.
Astronomers are looking for similar glows in other galaxies. But it may take a detection in the laboratory or in particle colliders to confirm the existence of these dark particles.
Script by Damond Benningfield, Copyright 2014
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