Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory

TL;DR

This study searches for energy-dependent patterns in cosmic ray arrival directions at the Pierre Auger Observatory but finds no significant patterns, providing constraints for astrophysical models of cosmic-ray sources and propagation.

Contribution

It introduces a method to analyze local regions around high-energy cosmic rays for energy-dependent patterns using two independent approaches, setting constraints on cosmic-ray deflection and source density.

Findings

No significant energy-dependent patterns detected.

Constraints placed on cosmic-ray deflection strength.

Limits on the density of cosmic-ray point sources.

Abstract

Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with $E \geq 6 \cdot 10^{19}$ eV by analyzing cosmic rays with energies above $E = 5 \cdot 10^{18}$ eV arriving within an angular separation of approximately $15{\deg}$. We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis. The comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources.