We argue that the anomalously high fluxes of positrons and antiprotons found in cosmic rays (CR) can be satisfactorily explained by introducing two additional elements to the current “standard” paradigm of Galactic CRs. First, we propose that the antiparticles are effectively produced in interactions of primary CRs with the surrounding gas not only in the interstellar medium (ISM) but also inside the accelerators. Secondly, we postulate the existence of two source populations injecting CRs into the ISM with different, (1) soft (close to $FI\propto E^{-2.3}$) and (2) hard ($FII\propto E^{-1.8}$ or harder), energy distributions. Assuming that CRs in the second population of accelerators accumulate “grammage” of the order of $1\mathrm{g}/{\mathrm{cm}}^2$ before their leakage into ISM, we can explain the energy distributions and absolute fluxes of both positrons and antiprotons, as well as the fluxes of secondary nuclei of the (Li, Be, B) group. The superposition of contributions of two source populations also explains the reported hardening of the spectra of CR protons and nuclei above 200 GV. The second source population accelerating CRs with a rate at the level below 10% of the power of the first source population can be responsible for the highest energy protons and nuclei of Galactic CRs up to the “knee” around ${10}^{15}\mathrm{eV}$.

• Received 18 December 2018
• Revised 28 March 2019

DOI:https://doi.org/10.1103/PhysRevD.100.063020