Origin of Cosmic Rays

With the use of recent observations of the galactic gas and $\gamma$-ray distributions, the galactic cosmic-ray distribution is deduced. This distribution is identical to that of supernova remnants (within experimental error), strongly supporting the hypothesis that most observed cosmic rays are produced by supernovae in our own galaxy. The average age of the cosmic-ray sources is suggested from the character of their distribution to be about 30 million years.