Volume 395 - 37th International Cosmic Ray Conference (ICRC2021) - CRD - Cosmic Ray Direct
Towards Understanding the Origin of Cosmic-Ray Positrons
Z. Weng
Full text: pdf
Pre-published on: July 05, 2021
Published on:
Abstract
Precision measurements of cosmic-ray positron flux by the Alpha Magnetic Spectrometer on the International Space Station are presented based on 1.9 million positrons up to 1 TeV.
The positron flux exhibits distinct and complex energy dependence.
The positron flux exhibits a significant excess starting from $25.2 \pm 1.8$\,GeV followed by a sharp drop-off above $284^{+91}_{-64}$\,GeV. In the entire energy range, the positron flux is well described by the sum of a diffuse term associated with low energy secondary positrons produced in the collision of cosmic rays, and a new source term of high energy positrons with a finite energy cutoff. This cutoff energy of the source term is determined to be $810^{+310}_{-180}$\,GeV with a significance of more than $4 \sigma$.
These experimental data show that, at high energies, positrons predominantly originate either from dark matter collisions or from new astrophysical sources.
DOI: https://doi.org/10.22323/1.395.0122
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