Towards Understanding the Origin of Cosmic-Ray Electrons

Precision results on cosmic-ray electrons are presented in the energy range from 0.5 GeV to 1.4 TeV based on 28.1 x 10$^{6}$ electrons collected by the Alpha Magnetic Spectrometeron the International Space Station. In the entire energy range the electron and positronspectra have distinctly different magnitudes and energy dependences. The electron flux exhibits a significant excess starting from 42.1$^{+5.4}_{-5.2}$ GeV compared to the lower energy trends, but the nature of this excess is different from the positronflux excess above 25.2 ± 1.8 GeV. Contrary to the positronflux, which has an exponential energy cutoff of 810$^{+310}_{-180}$ GeV, at the 5σ level the electron flux does not have an energy cutoff below 1.9 TeV. In the entire energy range the electron flux is well described by the sum of two power law components. The different behavior of the cosmic-ray electrons and positronsmeasured by the Alpha Magnetic Spectrometeris clear evidence that most high energy electrons originate from different sources than high energy positrons.