AMS-02 Results Support the Secondary Origin of Cosmic Ray Positrons

2013/05/31 by Kfir Blum, Boaz Katz, Eli Waxman · 6 citations
Physics and Astronomy · #Annihilation #Astrophysics #Astrophysics and Cosmic Phenomena #Cosmic ray #Dark Matter and Cosmic Phenomena #Dark matter #Electron #Galaxy #Milky Way #Nuclear physics #Particle physics theoretical and experimental studies #Physics #Positron #Pulsar #Rigidity (electromagnetism) #astro-ph.HE #hep-ph

paper · pdf · doi:10.1103/physrevlett.111.211101

published as Phys. Rev. Lett. 111, 211101 (2013) · 6 pages, 7 figures. v2: include updated results from AMS02 (B/C, e+ flux), match journal version

arxiv created 2013/11/09 · openalex publication_date 2013/11/20 · arxiv updated 2013/11/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We show that the recent AMS-02 positron fraction measurement is consistent with a secondary origin for positrons and does not require additional primary sources such as pulsars or dark matter. The measured positron fraction at high energy saturates the previously predicted upper bound for secondary production, obtained by neglecting radiative losses. This coincidence, which will be further tested by upcoming AMS-02 data at higher energy, is a compelling indication for a secondary source. Within the secondary model, the AMS-02 data imply a cosmic ray propagation time in the Galaxy of <10(6) yr and an average traversed interstellar matter density of ~1 cm(-3), comparable to the density of the Milky Way gaseous disk, at a rigidity of 300 GV.

Citations

• PAMELA Measurements of Cosmic-Ray Proton and Helium Spectra
• First Result from the Alpha Magnetic Spectrometer on the International Space Station: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5–350 GeV
• Measurements of cosmic-ray secondary nuclei at high energies with the first flight of the CREAM balloon-borne experiment

Cited by

• Cosmic ray signatures of a 2–3 Myr old local supernova
• High Statistics Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5–500 GeV with the Alpha Magnetic Spectrometer on the International Space Station
• Galactic factories of cosmic-ray electrons and positrons
• Theoretical Interpretation of Pass 8 Fermi-LAT e+ + e− Data
• ORIGIN OF THE COSMIC RAY POSITRONS OBSERVED NEAR EARTH: MESON DECAY OR DARK MATTER DECAY?
• On particle acceleration and transport in plasmas in the Galaxy: theory and observations