A possible correlation between the high energy electron spectrum and the cosmic-ray secondary-to-primary ratios

TL;DR

This paper explores a potential link between the high-energy electron spectrum and secondary-to-primary cosmic-ray ratios, proposing a model involving supernova remnants to explain observed spectral features and their correlation.

Contribution

It introduces a model connecting the spectral breaks in electrons and cosmic-ray ratios to supernova remnant confinement and release processes.

Findings

Spectral break at around 1 TeV in electron spectrum

Flattening of secondary-to-primary ratios at ~100 GeV/n

Proposed correlation between electron spectrum and cosmic-ray ratios

Abstract

Recent observations of high energy cosmic-ray electrons by the Fermi-LAT and the HESS experiments between $20$ GeV and $5$ TeV have found that the energy spectrum closely follow a broken power-law with a break at around $1$ TeV. On the other hand, measurements of cosmic-ray secondary-to-primary ratios like the boron-to-carbon ratio seem to indicate a possible change in the slope at energies around $100$ GeV/n. In this paper, we discuss one possible explanation for the observed break in the electron spectrum and its possible correlation with the flattening in the secondary-to-primary ratios at higher energies. In our model, we assume that cosmic-rays after acceleration by supernova remnant shock waves, escape downstream of the shock and remain confined within the remnant until the shock slows down. During this time, the high-energy electrons suffer from radiative energy losses and the cosmic-ray nuclei undergo nuclear fragmentations due to their interactions with the matter. Once the cosmic-rays are released from the supernova remnants, they follow diffusive propagation in the Galaxy where they further suffer from radiative or fragmentation losses.