Two spacecraft have detected a possible signal of dark matter, the mysterious, invisible stuff that makes up most of the material universe.
NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton satellite spotted a spike of X-ray emission coming from more than 70 different galaxy clusters. While the origin of the X-rays remains unclear at the moment, they could be generated by the decay of a certain type of dark-matter particle, scientists said.
"We know that the dark matter explanation is a long shot, but the payoff would be huge if we're right," study lead author Esra Bulbul, of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts, said in a statement. "So we're going to keep testing this interpretation and see where it takes us." [Gallery: Dark Matter Throughout the Universe]