Cosmic Ray Anisotropy with 11 Years of IceCube Data

TL;DR

This study analyzes 11 years of IceCube data to map cosmic-ray anisotropy in the Southern Hemisphere, revealing energy-dependent variations and solar cycle effects with improved statistical significance.

Contribution

It provides the most detailed anisotropy map to date with a larger dataset, showing energy-dependent changes and solar cycle variability in cosmic-ray arrival directions.

Findings

Enhanced significance of anisotropy at 6° scales.

Variation in angular power spectrum with energy.

Observation of solar cycle-related variability.

Abstract

The IceCube Observatory provides our highest-statistics picture of the cosmic-ray arrival directions in the Southern Hemisphere, with over 700 billion cosmic-ray-induced muon events collected between May 2011 and May 2022. Using the larger data volume, we find an improved significance of the PeV cosmic ray anisotropy down to scales of $6^\circ$. In addition, we observe a variation in the angular power spectrum as a function of energy, hinting at a relative decrease in large-scale features above 100 TeV. The data-taking period covers a complete solar cycle, providing new insight into the time variability of the signal. We present preliminary results using this up-to-date event sample.