Twelve Years of IceCube Data Unveil New Insights into Cosmic Ray Anisotropy

* This study uses data from the IceCube Neutrino Observatory, a massive detector at the South Pole, to study cosmic rays.

* The IceCube detector is primarily designed to detect high-energy neutrinos. However, it also collects a large amount of data on cosmic-ray muons.

* Muons are created when cosmic rays collide with the Earth's atmosphere.

* By studying the arrival directions of these muons, scientists can learn about the anisotropy of cosmic rays, meaning the variations in their arrival directions.

* This analysis used twelve years of data, from May 13, 2011, to May 12, 2023, resulting in the largest data sample ever collected by IceCube for this type of study.

* The analysis confirmed a change in the angular structure of cosmic-ray anisotropy between energies of 10 TeV and 1 PeV.

* This change is particularly noticeable in the 100 TeV to 300 TeV energy range.

* The researchers found that the anisotropy cannot be described as a simple dipole but is a complex pattern that changes with energy.

* They calculated the angular power spectrum of the anisotropy to understand the contribution of different angular scales to the overall pattern.

* The power spectrum analysis suggests that large-scale features of the anisotropy are relatively reduced at high energies compared to medium and small-scale features.

* This finding may provide insights into the origin and propagation of cosmic rays.

Reference: R. Abbasi et al., "Observation of Cosmic-Ray Anisotropy in the Southern Hemisphere with Twelve Years of Data Collected by the IceCube Neutrino Observatory." Submitted to ApJ (draft version December 9, 2024), arXiv:2412.05046v1.pdf.

Acknowledements: Podcast prepared with Google/NotebookLM. Illustration credits: IceCube collaboration