Observation of Cosmic-Ray Anisotropy in the Southern Hemisphere with 12 yr of Data Collected by the IceCube Neutrino Observatory
Date
2025-03-07
Journal Title
Journal ISSN
Volume Title
Publisher
The Astrophysical Journal
Abstract
We analyzed the 7.92 × 1011 cosmic-ray-induced muon events collected by the IceCube Neutrino Observatory from 2011 May 13, when the fully constructed experiment started to take data, to 2023 May 12. This data set provides an up-to-date cosmic-ray arrival direction distribution in the Southern Hemisphere with unprecedented statistical accuracy covering more than a full period length of a solar cycle. Improvements in Monte Carlo event simulation and better handling of year-to-year differences in data processing significantly reduce systematic uncertainties below the level of statistical fluctuations compared to the previously published results. We confirm the observation of a change in the angular structure of the cosmic-ray anisotropy between 10 TeV and 1 PeV, more specifically in the 100–300 TeV energy range. For the first time, we analyzed the angular power spectrum at different energies. The observed variations of the power spectra with energy suggest relatively reduced large-scale features at high energy compared to those of medium and small scales. The large volume of data enhances the statistical significance at higher energies, up to the PeV scale, and smaller angular scales, down to approximately 6° compared to previous findings.
Description
Please see publication for complete list of co-authors. This article was originally published in The Astrophysical Journal. The version of record is available at: https://doi.org/10.3847/1538-4357/adb1de.
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence (https://creativecommons.org/licenses/by/4.0/). Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
© 2025. The Author(s). Published by the American Astronomical Society.
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Citation
Abbasi, R., M. Ackermann, J. Adams, S. K. Agarwalla, T. Aguado, J. A. Aguilar, M. Ahlers, et al. “Observation of Cosmic-Ray Anisotropy in the Southern Hemisphere with 12 Yr of Data Collected by the IceCube Neutrino Observatory.” The Astrophysical Journal 981, no. 2 (March 2025): 182. https://doi.org/10.3847/1538-4357/adb1de.