Latest Results from the Alpha Magnetic Spectrometer on the International Space Station

TL;DR

This paper presents recent AMS measurements of cosmic ray electrons and positrons, revealing complex spectral features and a plateau in positron fraction above 200 GeV, indicating a common source.

Contribution

It provides new high-precision data on electron and positron fluxes and their ratio, extending the energy range and refining the understanding of cosmic ray sources.

Findings

Electron and positron fluxes deviate from simple power laws.

Positron fraction peaks and then plateaus above 200 GeV.

Evidence supports a common source for electrons and positrons.

Abstract

I review latest results from AMS on electrons and positrons in primary cosmic rays in the GeV to TeV energy range. Separate fluxes for electrons and positrons as well as their sum are presented. Neither of the fluxes is compatible with a simple power law. New data on the fraction of positrons in the joint electron and positron flux are also presented, which extend the energy range of our previous observation and increase its precision. The new results show, for the first time, that above about 200 GeV the positron fraction no longer exhibits an increase with energy. The results confirm that a common new source of electrons and positrons exists.