Anomaly in the cosmic-ray energy spectrum at GeV-TeV energies

TL;DR

This paper investigates the spectral hardening of cosmic rays at GeV-TeV energies, proposing that re-acceleration by old supernova remnants could be a key factor behind this phenomenon.

Contribution

It introduces the hypothesis that re-acceleration by weak shocks from old supernova remnants explains the spectral hardening in cosmic-ray energy spectra.

Findings

Spectral hardening observed at TeV energies.

Re-acceleration by supernova remnants can account for the spectral features.

Supports the re-acceleration hypothesis with theoretical considerations.

Abstract

Recent measurements of cosmic rays by various experiments have found that the energy spectrum of cosmic rays is harder in the TeV region than at GeV energies. The origin of the spectral hardening is not clearly understood. In this paper, we discuss the possibility that the spectral hardening might be due to the effect of re-acceleration of cosmic rays by weak shocks associated with old supernova remnants in the Galaxy.