Ankle phenomenon in the cosmic ray energy spectrum

TL;DR

The paper proposes a novel explanation for the knee and ankle features in the cosmic ray spectrum based on different expansion regimes of an expanding heat bath, aligning with recent observational data.

Contribution

It introduces a model linking cosmic ray spectral features to expansion phases of an expanding heat bath, predicting high-energy cosmic ray origins from AGN.

Findings

Predicted the knee at 3 PeV as a split between radiation and matter expansion.

Explained the ankle at 3 EeV via inflational and material expansion split.

Spectral indices match theoretical calculations from expansion rates.

Abstract

The author has suggested that the knee phenomenon in the cosmic ray energy spectrum at 3 PeV can be explained as a split between a radiation-dominated expansion and a matter-dominated expansion of an expanding heat bath. The model proposed in 1985, in fact, predicted that high energy cosmic rays are emitted from AGN, massive black holes, in agreement with recent data from the Pierre Auger Observatory. Similarly, the ankle phenomenon at 3 EeV is shown to be explained by a split between inflational expansion and ordinary material expansion of the expanding heat bath, not unlike that in the expansion of the universe. All the spectral indicies in the respective regions of the energy spectra agree with the theoretical calculation from the respective expansion rates.