Interpretation of the CALET Electron+Positron Spectrum by Astrophysical Sources

Abstract

The ISS-based Calorimetric Electron Telescope (CALET) is directly measuring the energy spectrum of electron+positron cosmic rays up to 20 TeV. Supernova remnants (SNR) are the most likely astrophysical sources to provide the majority of the electron flux, out of which a few nearby young SNR like Vela are expected to dominate in the TeV-region with potentially detectable spectral signatures. Another expected contribution to the spectrum is from pulsars as a primary positron-electron pair source for explanation of the positron excess. Complementary to the CALET all-electron spectrum, the positron-only spectrum measured by the magnet spectrometer AMS-02 below the TeV range provides detailed information on this component. An interpretation of the CALET and AMS-02 data by overlapping spectra from individual pulsar and SNR point sources is presented, combining sources known from electromagnetic wave observations with further randomly generated ones spread throughout the galaxy. Based on the study of a large number of samples with randomized source locations and emission spectra parameters, best fitting ranges and constraints for these parameters, as well as predictions for the spectrum beyond the so far measured energy range have been derived.