Galactic Streams of Cosmic-ray Electrons and Positrons
  Isotropic diffusion is a key assumption in many models of cosmic-ray
electrons and positrons. We find that simulation results imply a critical
energy of ~10-1000~GeV above which electrons and positrons can spend their
entire lives in streams threading magnetic fields, due to energy losses. This
would restrict the number of electron/positron sources contributing at Earth,
likely leading to smooth electron/positron spectra, as is observed. For
positrons, this could be as few as one, with an enhanced flux that would ease
energetics concerns of a pulsar origin of the positron excess, or even zero,
bringing dark matter to the fore. We conclude that ideas about
electron/positron propagation must be revised and discuss implications for
recent AMS-02 data.
