Energy-dependent anisotropy of cosmic-ray muons: A twelve-year study with IceCube Neutrino Observatory

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Autori principali: Dhakal, Nabin Upadhya, Bhusal, Nabin, Kunwar, Manjeet, Khatiwada, Manil, Yadav, Shiv Narayan
Natura: Preprint
Pubblicazione: 2025
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author Dhakal, Nabin Upadhya
Bhusal, Nabin
Kunwar, Manjeet
Khatiwada, Manil
Yadav, Shiv Narayan
author_facet Dhakal, Nabin Upadhya
Bhusal, Nabin
Kunwar, Manjeet
Khatiwada, Manil
Yadav, Shiv Narayan
contents We present a comprehensive, energy-resolved study of cosmic-ray muon anisotropy using 12 years (2011-2023) of data from the IceCube Neutrino Observatory, comprising 7.92 x 10^11 events in the 13 TeV to 5.3 PeV energy range. Dividing the spectrum at log-scale energy 5 GeV, we contrast low- and high-energy anisotropy features via sidereal modulation, angular profiles, Fourier analysis, and full-sky HEALPix mapping. Gaussian and power-law fits to energy distributions are evaluated using chi-squared, reduced chi-squared, and Bayesian Information Criterion. Results show strong dipolar and large-scale anisotropy at low energies, likely due to geomagnetic and atmospheric effects, while high-energy muons display weaker, more localized structures consistent with reduced scattering and source-related anisotropy. Energy distributions are well fit by Gaussians, especially in the 6.5 to 100 bin, validating IceCube's reconstruction at PeV scales. These findings confirm energy-dependent anisotropy and support cosmic-ray diffusion models.
format Preprint
id arxiv_https___arxiv_org_abs_2508_01194
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Energy-dependent anisotropy of cosmic-ray muons: A twelve-year study with IceCube Neutrino Observatory
Dhakal, Nabin Upadhya
Bhusal, Nabin
Kunwar, Manjeet
Khatiwada, Manil
Yadav, Shiv Narayan
High Energy Astrophysical Phenomena
Cosmology and Nongalactic Astrophysics
We present a comprehensive, energy-resolved study of cosmic-ray muon anisotropy using 12 years (2011-2023) of data from the IceCube Neutrino Observatory, comprising 7.92 x 10^11 events in the 13 TeV to 5.3 PeV energy range. Dividing the spectrum at log-scale energy 5 GeV, we contrast low- and high-energy anisotropy features via sidereal modulation, angular profiles, Fourier analysis, and full-sky HEALPix mapping. Gaussian and power-law fits to energy distributions are evaluated using chi-squared, reduced chi-squared, and Bayesian Information Criterion. Results show strong dipolar and large-scale anisotropy at low energies, likely due to geomagnetic and atmospheric effects, while high-energy muons display weaker, more localized structures consistent with reduced scattering and source-related anisotropy. Energy distributions are well fit by Gaussians, especially in the 6.5 to 100 bin, validating IceCube's reconstruction at PeV scales. These findings confirm energy-dependent anisotropy and support cosmic-ray diffusion models.
title Energy-dependent anisotropy of cosmic-ray muons: A twelve-year study with IceCube Neutrino Observatory
topic High Energy Astrophysical Phenomena
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2508.01194