Cosmic rays from supernovae

Credit: NASA|DOE|Fermi LAT Collaboration

Cosmic rays are energetic particles that stream through the universe. Some slam into Earth’s atmosphere, triggering a cascade of other particles detectable on the ground. A popular theory in astrophysics holds that cosmic rays are created in supernovas.Until now this has been difficult to prove due to the considerable distance cosmic rays must travel before they reach Earth. In addition magnetic forces can deflect cosmic rays during their trip through space, confusing our sense of their origin.Some theories predict that some of the supernovae cosmic rays crash into nearby gas clouds in space, where they convert into gamma light. Unaffected by magnetism in space, it is this light that continues on toward Earth, eventually striking the Fermi telescope.The telescope acts like a huge digital camera taking pictures of the supernova debris. Because it can take hundreds or thousands of years for the light to complete the trip to our planet, the light that we can currently see shows the supernova as it was centuries or millennia ago. Stanford physicist Stefan Funk said that the gamma pictures, combined with observations made with other telescopes sensitive to other kinds of light, allowed astronomers to confirm that many high-energy cosmic rays come from supernovas.Phillip F. ScheweInside Science News ServiceEdited by Paul Guinnessy