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