Signature of Energy Losses on the Cosmic Ray Electron Spectrum

Abstract

We show that the fine structure of the electron spectrum in cosmic rays, especially the excess claimed by AMS-02 at energies $\sim$42 GeV, is fully accounted for in terms of inverse Compton losses in the photon background dominated by ultraviolet, infrared and CMB photons, plus the standard synchrotron losses in the Galactic magnetic field. The transition to the Klein-Nishina regime on the ultraviolet background causes the feature. Hence, contrary to previous statements, observations do not require the overlap of different components. We stress that the feature observed by AMS-02 at energies $\sim$42 GeV is not related to the positron excess, which instead requires the existence of positron sources, such as pulsars. Because energy losses are the physical explanation of this feature, we indirectly confirm that the transport of leptons in the Galaxy is loss-dominated down to energies of the order of tens of GeV. This finding imposes strong constraints on the feasibility of alternative theories of cosmic transport in which the grammage is accumulated in cocoons concentrated around sources, requiring that electrons and positrons become loss dominated only at very high energies.

5 pages, 3 figures, minor updates in the text, fixed a typo in Eq. 4

References in corpus (7)

• Analytical solutions for energy spectra of electrons accelerated by nonrelativistic shock-waves in shell type supernova remnants
• Galactic electrons and positrons at the Earth:new estimate of the primary and secondary fluxes
• A radiation transfer model for the Milky-Way: I. Radiation fields and application to High Energy Astrophysics
• Galactic cosmic rays after the AMS-02 observations
• AMS-02 beryllium data and its implication for cosmic ray transport
• Indications for a high-rigidity break in the cosmic-ray diffusion coefficient
• Interpretation of the cosmic ray positron and antiproton fluxes

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