Contact: Andy Freeberg
DOE/SLAC National Accelerator Laboratory
Caption: When stars explode, the supernovas send off shock waves, which accelerate protons to cosmic-ray energies through a process known as Fermi acceleration. In this mechanism, named for Enrico Fermi who first hypothesized it, the protons gain energy from collisions with turbulent magnetic fields on either side of a shock wave. Though many details of Fermi acceleration remain unknown, new results from the Fermi Gamma-ray Space Telescope provide overwhelming evidence that the mechanism is indeed responsible for producing many of the galaxy's cosmic ray protons.
Credit: Greg Stewart, SLAC National Accelerator Laboratory
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Related news release: Proof: Cosmic rays come from exploding stars