"Scientists have been trying to find the sources of high-energy
cosmic rays since their discovery a century ago," said Elizabeth
Hays, a member of the research team and Fermi deputy project
scientist at NASA's Goddard Space Flight Center in Greenbelt,
Md. "Now we have conclusive proof supernova remnants, long the
prime suspects, really do accelerate cosmic rays to incredible
speeds." Cosmic rays are subatomic particles that move through
space at almost the speed of light. About 90 percent of them are
protons, with the remainder consisting of electrons and atomic
nuclei. In their journey across the galaxy, the electrically
charged particles are deflected by magnetic fields. This
scrambles their paths and makes it impossible to trace their
origins directly. Through a variety of mechanisms, these speedy
particles can lead to the emission of gamma rays, the most
powerful form of light and a signal that travels to us directly
from its sources. Since its launch in 2008, Fermi's Large Area
Telescope (LAT) has mapped