Cosmic ray anisotropies to 5 PeV

TL;DR

This paper analyzes cosmic ray anisotropies up to 5 PeV, revealing energy-dependent directional changes and potential links to supernova remnants, based on recent and historical data from multiple detectors.

Contribution

It provides a comprehensive analysis of cosmic ray anisotropies up to 5 PeV, highlighting energy-dependent phase and amplitude changes and discussing potential astrophysical sources.

Findings

Anisotropy amplitude rises, diminishes, then rises again with energy.

Phase of anisotropy shifts to opposite direction at higher energies.

CR excess moves from Galactic Anti-Centre to Galactic Centre at PeV energies.

Abstract

Several large cosmic ray (CR) detectors have recently provided data on the arrival directions of CR, which taken together with previous data recorded over many decades allow the amplitgude and phase of the first harmonic to be derived with reasonable precision and up to higher energies. We find a high degree of consistency amongst the various measurements. The new data indicate that at an energy above ~0.1 PeV a change of the CR anisotropy sets in. The amplitude of the first harmonic, which rises to 3 TeV, then diminishes and begins to rise again. The direction of the phase also changes to the opposite one. A measure of understanding follows from the use of two-dimensional maps of CR excesses over the mean background. When the energy of CR approaches the PeV region, the excess of CR moves from the Galactic Anti-Centre to the opposite direction of the Galactic Centre. The possible role of such potential CR sources as the supernovae Monogem Ring and Vela, which could help to explain some of the observed results, is discussed.