To find out if this could explain the heavy cosmic rays, Kusenko's team calculated the numbers of protons and nuclei that such explosions would produce and whether the Milky Way's magnetic field would be able to retain them.
At low energies, both protons and nuclei were deflected by the magnetic field and therefore retained in the galaxy for millions of years. But at high energies, the protons tended to escape while the heavier, less mobile nuclei hung around.
This could account for the increase in heavy cosmic rays seen at high energies by Auger, say the team. "Gamma ray bursts inject high-energy nuclei that get trapped in the galactic magnetic field and are observed some million years later as cosmic rays," says Kusenko."