Scientists studying data gathered by the cosmic ray detector PAMELA say the accepted theory on their origin may need to be corrected or completely eliminated.

Cosmic rays are steams of particles, mostly electrons, positrons and helium nuclei, with very high energy. Astronomers believe that they come from the remains of stars that go supernova. Such a catastrophic event produces strong magnetic fields, which linger for millennia and can serve as natural particle accelerators, producing cosmic rays.

PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Аstrophysics) is a cosmic ray detector mounted on a Russian earth surveillance satellite which has been collecting data since 2006. Now a group of Italian, Russian, Swedish and German scientists say the data is not in line with the previous theory.

In a paper published in Science magazine, the authors say the energy spectrum of the particles detected by PAMELA is too wide for all of them to have come from supernovae. The scientists speculate that at least some of the cosmic rays must have come from different sources somewhere closer to the Solar system. These sources may be stars similar in size to the Sun, but with higher activity, which can produce cosmic rays with lower energy that those produced by supernovae.