Evidence for the Moon and Sun shadows with cosmic rays at an average energy of 7 × 10 17 eV

Interactions of cosmic rays with the Moon and the Sun produce deficits in their arrival-direction distributions relative to an isotropic flux. Such shadows have been observed previously at energies between $10^{12}\,$eV and $10^{16}\,$eV. We report the first observation of the Moon and Sun shadows at cosmic-ray energies larger than about $10^{16}\,$eV (average energy of $7\times10^{17}\,$eV), using data collected by the Pierre Auger Observatory. We employ data from three detector arrays covering $3000\,\text{km}^2$, $27\,\text{km}^2$, and $2\,\text{km}^2$, with spacings of $1500\,\text{m}$, $750\,\text{m}$, and $433\,\text{m}$, respectively. The data amount to over 10.6 million events. The Moon and Sun shadows are detected with a combined significance of approximately $3σ$. These observations confirm the pointing accuracy of the Surface Detector of the Pierre Auger Observatory using celestial bodies. From the combined Sun and Moon shadows, we infer an overall angular resolution of $(0.59^{+0.15}_{-0.11})^\circ$.

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Publication Details

Journal
Physical review. D/Physical review. D.
Published
2026-11-09
DOI
https://doi.org/10.1103/qdw9-tbz2
Primary Topic
Astrophysics and Cosmic Phenomena
Type
article
Field-Weighted Citation Impact
0.00

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article

Evidence for the Moon and Sun shadows with cosmic rays at an average energy of 7 × 10 17 eV

A. Ambrosone, N. Denner, T. Dominguez, J. Brack et al.
2 links
Physical review. D/Physical review. D.
Astrophysics and Cosmic Phenomena
article

Evidence for the Moon and Sun shadows with cosmic rays at an average energy of 7 × 10 17 eV

A. Ambrosone, N. Denner, T. Dominguez, J. Brack, V. de Souza, N. Borodai, C. Aramo, J. R. T. de Mello Neto, I. De Mitri, P. Abreu, J. A. Chinellato, P. G. Brichetto Orquera, F. Convenga, R. Caruso, E. De Vito, D. de Oliveira Franco, M. Aglietta, T. Dominguez, M. E. Bertaina, K. Bismark, S. J. de Jong, N. Denner, K. Cerny, A. Del Popolo, J. de Jesús, V. Binet, P. L. Biermann, R. M. de Almeida, A. C. Cobos Cerutti, A. Baluta, M. Cristinziani, F. Catalani, B. Čermáková, O. Deligny, B. de Errico, S. Dasso, G. Avila, J. Biteau, C. S. Cruz Sanchez, A. Bakalova, L. Deval, S. Buitink, A. Bartz Mocellin, T. R. Caba Pineda, K. Almeida Cheminant, G. Cataldi, K. S. Caballero-Mora, A. Cermenati, L. Andrade Dourado, R. Colalillo, J. Alvarez-Muñiz, F. de Palma, K. Daumiller, A. Bwembya, E. Avocone, G. Consolati, L. Caccianiga, O. Batalla Cruz, J. Blazek, P. Assis, I. Allekotte, D. Boncioli, R. Conceição, J. Blümer, M. Conte, M. Ahmed, J. Caraça-Valente, M. Bianciotto, L. Apollonio, L. Anchordoqui, J. Chudoba, L. Chytka, C. Dobrigkeit, P. J. Costa, D. Correia dos Santos, A. di Matteo, Q. Dorosti, B. Andrada, A. Castellina, M. Cerda, A. Abdul Halim, A. Ambrosone, J. P. Behler, S. Cabana-Freire, R. W. Clay, R. Aloisio, M. Boháčová, L. M. Domingues Mendes, Y. Balibrea, E.-T. de Boone, L. Cazon, B. R. Dawson, J. C. Arteaga Velázquez, J. C. D’Olivo, C. E. Covault, C. Berat, C. Bonifazi, F. Barbato, R. C. dos Anjos, T. Bister
article en

Abstract

Interactions of cosmic rays with the Moon and the Sun produce deficits in their arrival-direction distributions relative to an isotropic flux. Such shadows have been observed previously at energies between $10^{12}\,$eV and $10^{16}\,$eV. We report the first observation of the Moon and Sun shadows at cosmic-ray energies larger than about $10^{16}\,$eV (average energy of $7\times10^{17}\,$eV), using data collected by the Pierre Auger Observatory. We employ data from three detector arrays covering $3000\,\text{km}^2$, $27\,\text{km}^2$, and $2\,\text{km}^2$, with spacings of $1500\,\text{m}$, $750\,\text{m}$, and $433\,\text{m}$, respectively. The data amount to over 10.6 million events. The Moon and Sun shadows are detected with a combined significance of approximately $3σ$. These observations confirm the pointing accuracy of the Surface Detector of the Pierre Auger Observatory using celestial bodies. From the combined Sun and Moon shadows, we infer an overall angular resolution of $(0.59^{+0.15}_{-0.11})^\circ$.

Physical review. D/Physical review. D.
National Science Foundation, U.S. Department of Energy, Grainger Foundation, Strong, Ministerio de Ciencia, Innovación y Universidades, European Commission, Deutsche Forschungsgemeinschaft, Ministerstvo Školství, Mládeže a Tělovýchovy, Grantová Agentura České Republiky, Fonds De La Recherche Scientifique - FNRS, Consejo Nacional de Investigaciones Científicas y Técnicas, Fonds Wetenschappelijk Onderzoek, Consejo Nacional de Ciencia y Tecnología, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Ministério da Ciência, Tecnologia e Inovação, Centre National de la Recherche Scientifique, Istituto Nazionale di Astrofisica, Universidad Nacional Autónoma de México, Benemérita Universidad Autónoma de Puebla, Xunta de Galicia, Vlaamse regering, Istituto Nazionale di Fisica Nucleare, Ministerium für Kultur und Wissenschaft des Landes Nordrhein-Westfalen, Helmholtz Alliance for Astroparticle Physics, Ministero dell'Università e della Ricerca, Fundação para a Ciência e a Tecnologia, Agencia Nacional de Promoción Científica y Tecnológica, European Regional Development Fund, Agencia Estatal de Investigación, Institut National de Physique Nucléaire et de Physique des Particules
Astrophysics and Cosmic Phenomena
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