Distribution and lifetime of cosmic-ray electrons in the galaxy

Abstract

When the source spectrum of cosmic-ray electrons has the form E−γ, the equilibrium spectrum is expected to approach E−γ−1 above a critical energy Ec, where Ec is a function of the storage time and the energy loss rate due to synchrotron radiation and the inverse Compton effect. The observed electron spectrum, which is a combination of the latest results of the Minnesota group, Chicago group, Bombay group, and Leiden group, can be well expressed by a single power law (~E−2.5) for 3 < E < 100 GeV. A knee observed at about 3 GeV might also be due to a solar effect.Thus the possibilities are either [Formula: see text] or Ec > 50 GeV. These two cases lead to largely different models with respect to the source spectrum, the acceleration, the storage time, and the distribution of cosmic-ray electrons in the galaxy. The radio observations are compatible with the hypothesis based on [Formula: see text].