Cosmic Ray Spectrum and Plasma Turbulence

Abstract

The main features of the observed cosmic ray electron and ion spectra are considered as fundamental properties of cosmic rays. It is asked whether it is possible to obtain from these properties any information about the physical parameters in the cosmic ray sources. The modern theory of plasma turbulence is applied to this question. It is shown that the observed power law spectra of cosmic rays fe ~ 1/eY (fe — the distribution function in energies e; ∫ fede = n* — the density of cosmic rays) with average γ near to 2.7 give very rigid restrictions for possible mechanisms of acceleration and of energy losses of cosmic rays. Both must be very effective, be correlated with each other, and essentially exceed the usual energy losses of cosmic rays in a quiet plasma. The ratio of the diffusion coefficient D(e) in energy space that describes the acceleration, to the energy losses of a single particle per unit time A(e), must be, with good accuracy, proportional to the energy D(e)/A(e) = ae, with the constant coefficient a of order unity.