An anti-knee

TL;DR

This paper simulates cosmic ray energy spectra for various elements, revealing oscillations and a novel 'anti-knee' feature in the iron spectrum at 2×10^{15} eV, based on supernova source models.

Contribution

It introduces the concept of an 'anti-knee' in cosmic ray spectra and models spectral features using supernova source superposition and diffusive shock acceleration.

Findings

Oscillations in spectral index γ across elemental groups.

Discovery of an increasing γ 'anti-knee' in Fe spectrum at 2×10^{15} eV.

Spectral features linked to supernova source contributions.

Abstract

The energy spectra for five elemental groups (p, He, C, Si, Fe) of cosmic rays, are simulated. Calculations are based on an analysis of superposition of few cosmic ray sources (Supernovae of different types) and principles of diffusive shock acceleration. Results of the analysis in the knee region show that summarizing energy spectra for elemental mass groups of cosmic rays can have significant oscillations of spectral index $\gamma$. Moreover, a kink (increasing $\gamma$) in Fe spectrum at energy $2\cdot 10^{15}$ eV, is discovered. In order to distinguish from the knee (decreasing $\gamma$) the kink can be called an anti-knee (increasing $\gamma$).