Interpretations of the cosmic ray secondary-to-primary ratios measured by DAMPE

Kavli Affiliate: Igor V. Moskalenko

| First 5 Authors: Peng-Xiong Ma, Zhi-Hui Xu, Qiang Yuan, Xiao-Jun Bi, Yi-Zhong Fan

| Summary:

Precise measurements of the boron-to-carbon and boron-to-oxygen ratios by
DAMPE show clear hardenings around $100$ GeV/n, which provide important
implications on the production, propagation, and interaction of Galactic cosmic
rays. In this work we investigate a number of models proposed in literature in
light of the DAMPE findings. These models can roughly be classified into two
classes, driven by propagation effects or by source ones. Among these models
discussed, we find that the re-acceleration of cosmic rays, during their
propagation, by random magnetohydrodynamic waves may not reproduce sufficient
hardenings of B/C and B/O, and an additional spectral break of the diffusion
coefficient is required. The other models can properly explain the hardenings
of the ratios. However, depending on simplifications assumed, the models differ
in their quality in reproducing the data in a wide energy range. The models
with significant re-acceleration effect will under-predict low-energy
antiprotons but over-predict low-energy positrons, and the models with
secondary production at sources over-predict high-energy antiprotons. For all
models high-energy positron excess exists.

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