A TANTALISING signal recorded high above Antarctica may be a telltale signature of dark matter, the mysterious stuff thought to make up a large proportion of the universe.
John Wefel of Louisiana State University in Baton Rouge and colleagues hung a detector called the Advanced Thin Ionization Calorimeter from a balloon and sent it flying over Antarctica to pick up the high-energy electrons from deep space that feature in cosmic rays. It found 70 more electrons in the 300 to 800-gigaelectronvolt energy range than were expected from known sources such as supernovae.
According to Wefel, there are two possible explanations. The electrons could come from a nearby cosmic object that astronomers have not yet identified. The team has spent four years trying to find an object to fit the signal and has yet to find a good match.
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The alternative is that the electrons were produced when two dark matter particles met and destroyed each other. The signature would be expected from a specific type of dark matter candidate called weakly interacting massive particles, or WIMPs (Nature, vol 456, p 362).
鈥淓ven if it proves not to be dark matter, the puzzle of how very high-energy cosmic rays are produced is still a mystery, and this work will help shed some light on it,鈥� says Andy Taylor at the University of Edinburgh, UK.