Cosmic-Ray Confinement in the Galaxy

Phenomenological models are examined which are used to interpret the available experimental data on the spectra, composition, and anisotropy of galactic cosmic rays with energies of less than 3 million GeV. The following types of models are reviewed: closed, leaky box, nested leaky box, diffusion, dynamical halo, very inhomogeneous, continuous acceleration, and extragalactic. Consideration is given to the physical mechanisms that govern cosmic-ray confinement and escape and to the interpretation of cosmic-ray observations at earth in terms of the above models. Observations of the diffuse gamma-ray emission of the galaxy are discussed which appear to rule out the extragalactic model. The problem of very high-energy cosmic rays (higher than 3 million GeV) is briefly noted.