VII - The Origin of Cosmic Rays

Abstract

This chapter discusses the origin of cosmic rays. The central problem of the cosmic ray physics is how and where the particles acquired their immense energies. The debate on the means by which cosmic rays acquire their energy turned in a new direction after a paper by Fermi. Even before the radio evidence for concentrations of relativistic electrons in the Crab nebula, it had been noted that supernova explosions might provide sufficient energy to maintain the cosmic radiation if much of the output went into relativistic particles. The nature of supernovae is still not well understood. Supernovae form a distinct group of intense stellar outbursts, in which a star, for several days, becomes intrinsically ∼ 10 9 –10 10 times as bright as the Sun, and then fades away over a period of months. The chapter also describes how it is possible to devise incomplete models for cosmic-ray production, which require more astronomical data to progress further.