Nonsecondary origin of cosmic ray positrons

Abstract

We investigate the possibility of secondary production as the source of cosmic ray (CR) positrons, taking into account observed electron and antiproton spectra and allowing that the reported steepening in the AMS-02 positron spectrum may be due to radiative losses. Using a simple argument based on the antiproton spectrum, we show that positrons cannot be purely secondary. Namely, the antiproton to positron ratio requires that positrons be uncooled up to a few hundred GeV. This requirement implies that CR protons escape from the Galaxy too quickly to reproduce the observed antiproton flux. We further show that this result rules out also more complex secondary production scenarios such as reacceleration and the Nested Leaky Box. Thus, we conclude that while antiprotons can be produced exclusively in secondary interactions, a primary source of CR positrons -- be it dark matter or pulsars -- is required to explain their spectrum.

arXiv comment7 pages, 2 figures, accepted for publication in PRD

References in corpus (30)

• The Interstellar Environment of our Galaxy
• PAMELA Measurements of Cosmic-ray Proton and Helium Spectra
• Direct detection of a break in the teraelectronvolt cosmic-ray spectrum of electrons and positrons
• Pulsars as the Sources of High Energy Cosmic Ray Positrons
• Discrepant hardening observed in cosmic-ray elemental spectra
• Energy Spectra of Abundant Nuclei of Primary Cosmic Rays from the Data of ATIC-2 Experiment: Final Results
• Cosmic-Ray Proton and Helium Spectra from the First CREAM Flight
• The origin of the positron excess in cosmic rays
• The cosmic-ray positron energy spectrum measured by PAMELA
• Spectral breaks as a signature of cosmic ray induced turbulence in the Galaxy
• Direct Measurement of the Cosmic-Ray Proton Spectrum from 50 GeV to 10 TeV with the Calorimetric Electron Telescope on the International Space Station
• Cosmic Ray Transport in the Galaxy: a Review
• High-energy antiprotons from old supernova remnants
• Energy Spectrum of Cosmic-ray Electron and Positron from 10 GeV to 3 TeV Observed with the Calorimetric Electron Telescope on the International Space Station
• Astrophysical models for the origin of the positron "excess"
• Galactic cosmic rays after the AMS-02 observations
• High Energy Positrons From Annihilating Dark Matter
• The contribution of supernova remnants to the galactic cosmic ray spectrum
• AMS-02 beryllium data and its implication for cosmic ray transport
• A Cosmic Ray Positron Anisotropy due to Two Middle-Aged, Nearby Pulsars?
• Production cross sections of cosmic antiprotons in the light of new data from the NA61 and LHCb experiments
• The origin of the spectral intensities of cosmic-ray positrons
• Interpretation of the cosmic ray positron and antiproton fluxes
• Spectral Intensities of Antiprotons and the lifetime of Cosmic Rays in the Galaxy
• On the Spectrum of Electrons Accelerated in Supernova Remnants
• The spectral shapes of the fluxes of electrons and positrons and the average residence time of cosmic rays in the Galaxy
• Plus Charge Prevalence in Cosmic Rays: Room for Dark Matter in the Positron Spectrum
• Multi-messenger constraints to the local emission of cosmic-ray electrons
• $e^{+}$ and $\bar{p}$ production in $pp$ collisions and the cosmic-ray $e^{+}/\bar{p}$ flux ratio
• Understanding the cosmic ray positron flux

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• New determination of the production cross section for secondary positrons and electrons in the Galaxy
• A novel prediction for secondary positrons and electrons in the Galaxy
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• On the contribution of the bow shock pulsar wind nebula PSR J0437-4715 to the observed fluxes of GeV-TeV positrons and antiprotons