A common origin of multi-messenger spectral anomaly of galactic cosmic rays

TL;DR

This paper proposes that slow diffusion zones around sources explain the spectral anomalies in galactic cosmic rays, distinguishing local high-energy particles from distant low-energy ones, and predicts spatial variations in diffuse gamma-ray spectra.

Contribution

It introduces a model incorporating slow diffusion zones to unify the explanation of cosmic ray spectral anomalies and predicts spatial dependence in gamma-ray emissions.

Findings

Successfully reproduces spectral anomalies with the model

Differentiates local high-energy and distant low-energy cosmic ray origins

Predicts spatial variation in diffuse gamma-ray spectra

Abstract

Recent observations of cosmic rays (CRs) have revealed a two-component anomaly in the spectra of primary and secondary particles, as well as their ratios, prompting investigation into their common origin. In this study, we incorporate the identification of slow diffusion zones around sources as a common phenomenon into our calculations, which successfully reproduces all previously described anomalies except for the positron spectrum. Crucially, our research offers a clear physical picture of the origin of CR: while high-energy ($\textrm{>200~GV}$, including the knee) particles are primarily produced by fresh accelerators and are confined to local regions, low energy ($\textrm{<200~GV}$) components come from distant sources and travel through the outer diffusive zone outside of the galactic disk. This scenario can be universally applied in the galactic disk, as evidenced by ultra-high energy diffuse $\rm\gamma$-ray emissions detected by the AS$\rm\gamma$ experiment. Furthermore, our results predict that the spectrum of diffuse $\rm\gamma$-ray is spatial-dependent, resting with local sources, which can be tested by LHAASO experiment.