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Main Author: Šimková, Katarína
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.08582
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author Šimková, Katarína
author_facet Šimková, Katarína
contents The interaction of cosmic rays with celestial bodies such as the Moon or the Sun produces a shadow in the arrival direction distribution of the cosmic rays reaching the Earth. Such deficits from an isotropic flux have been observed by astroparticle observatories below energies of $10^{15}\,$eV. Above this energy, measurements were limited due to the low number of events as a result of the steeply falling cosmic-ray flux with energy. With more than 10.6 million events recorded during 20 years of operation of the Pierre Auger Observatory, we report the first observation of the shadow of the Moon at an average energy of $7\times10^{17}\,$eV with a maximum significance above 3$σ$. The shadow is an end-to-end check that the celestial directions are correctly reconstructed from the air shower data, and it is used here to derive the effective angular resolution for this dataset. Additionally, we present the results of a similar study on the shadow of the Sun.
format Preprint
id arxiv_https___arxiv_org_abs_2507_08582
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Observation of the Shadows of the Moon and Sun Using the Pierre Auger Observatory at an Average Energy of $7\times10^{17}\,$eV
Šimková, Katarína
High Energy Astrophysical Phenomena
Instrumentation and Methods for Astrophysics
The interaction of cosmic rays with celestial bodies such as the Moon or the Sun produces a shadow in the arrival direction distribution of the cosmic rays reaching the Earth. Such deficits from an isotropic flux have been observed by astroparticle observatories below energies of $10^{15}\,$eV. Above this energy, measurements were limited due to the low number of events as a result of the steeply falling cosmic-ray flux with energy. With more than 10.6 million events recorded during 20 years of operation of the Pierre Auger Observatory, we report the first observation of the shadow of the Moon at an average energy of $7\times10^{17}\,$eV with a maximum significance above 3$σ$. The shadow is an end-to-end check that the celestial directions are correctly reconstructed from the air shower data, and it is used here to derive the effective angular resolution for this dataset. Additionally, we present the results of a similar study on the shadow of the Sun.
title Observation of the Shadows of the Moon and Sun Using the Pierre Auger Observatory at an Average Energy of $7\times10^{17}\,$eV
topic High Energy Astrophysical Phenomena
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2507.08582