for National Geographic News
High-energy electrons captured over Antarctica could reveal the presence of a nearby but mysterious astrophysical object that's bombarding Earth with cosmic rays, researchers say.
Or the electrons may be the long-awaited physical evidence of elusive dark matter.
Either way, the unusual particles are exciting for astrophysicists, who say they could someday confirm or deny decades of unproven theories.
"In the first case, we have now seen for the first time a nearby source of cosmic rays. Nobody's seen that before," said study co-author John Wefel, a physicist at Louisiana State University in Baton Rouge.
"In the second case, we may be seeing something even more stupendous."
Cosmic rays are not beams per se but are any protons, electrons, and other subatomic particles that careen toward Earth from a variety of sources, including the supernova explosions that mark the deaths of stars.
Most of the cosmic electrons that reach Earth are low-energy, because the highest-energy ones fizzle the fastest and don't last long enough to get here.
Capturing any electrons at all from the high end of the energy spectrum requires a sustained sampling effort.
The authors of the new study flew a balloon-borne particle collector called the Advanced Thin Ionization Calorimeter (ATIC) over Antarctica.
Circular winds at that latitude allow the balloon to stay aloft for up to 30 days at a time, capturing electrons and measuring their charges, energies, and trajectories.
The team got a surprise: ATIC found inflated numbers of high-energy electrons that match the signal expected from the destruction of dark matter.
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