Review of Cosmic Rays

Abstract

Photon astronomy is divided into areas covering different energy regimes, beginning with radio astronomy at the lowest, and ending with gamma-ray astronomy at the highest observable energies. The cosmic radiation on the other hand encompasses in a single area nuclear particles and electrons of astrophysical origin over a very wide energy range, extending from superthermal energies that just exceed those of the solar or stellar winds (≈10⁶eV) to particles that carry the largest quanta of energy observed in any astrophysical radiation, up to 10²¹ eV. Dealing with that wide a range in energy, one should not be surprised that the origin of this radiation and its behavior is likely to involve a variety of different physical phenomena. Also, the spectrum of cosmic rays has two dimensions, one in energy, and one in the species of the particles.