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arXiv · 2008.06488

Features of the energy spectrum of cosmic rays above $2.5{\times} 10^{18}$ eV using the Pierre Auger Observatory

The Pierre Auger Collaboration·A. Aab·P. Abreu·M. Aglietta·J. M. Albury·I. Allekotte·A. Almela·J. Alvarez Castillo·J. Alvarez-Muñiz·R. Alves Batista·G. A. Anastasi·L. Anchordoqui·B. Andrada·S. Andringa·C. Aramo·P. R. Araújo Ferreira·H. Asorey·P. Assis·G. Avila·A. M. Badescu·A. Bakalova·A. Balaceanu·F. Barbato·R. J. Barreira Luz·K. H. Becker·J. A. Bellido·C. Berat·M. E. Bertaina·X. Bertou·P. L. Biermann·T. Bister·J. Biteau·A. Blanco·J. Blazek·C. Bleve·M. Boháčová·D. Boncioli·C. Bonifazi·L. Bonneau Arbeletche·N. Borodai·A. M. Botti·J. Brack·T. Bretz·F. L. Briechle·P. Buchholz·A. Bueno·S. Buitink·M. Buscemi·K. S. Caballero-Mora·L. Caccianiga·L. Calcagni·A. Cancio·F. Canfora·I. Caracas·J. M. Carceller·R. Caruso·A. Castellina·F. Catalani·G. Cataldi·L. Cazon·M. Cerda·J. A. Chinellato·K. Choi·J. Chudoba·L. Chytka·R. W. Clay·A. C. Cobos Cerutti·R. Colalillo·A. Coleman·M. R. Coluccia·R. Conceição·A. Condorelli·G. Consolati·F. Contreras·F. Convenga·C. E. Covault·S. Dasso·K. Daumiller·B. R. Dawson·J. A. Day·R. M. de Almeida·J. de Jesús·S. J. de Jong·G. De Mauro·J. R. T. de Mello Neto·I. De Mitri·J. de Oliveira·D. de Oliveira Franco·V. de Souza·E. De Vito·J. Debatin·M. del Río·O. Deligny·H. Dembinski·N. Dhital·C. Di Giulio·A. Di Matteo·M. L. Díaz Castro·C. Dobrigkeit·J. C. D'Olivo
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Abstract

We report a measurement of the energy spectrum of cosmic rays above $2.5{\times} 10^{18}$ eV based on $215,030$ events. New results are presented: at about $1.3{\times} 10^{19}$ eV, the spectral index changes from $2.51 \pm 0.03 \textrm{ (stat.)} \pm 0.05 \textrm{ (sys.)}$ to $3.05 \pm 0.05 \textrm{ (stat.)}\pm 0.10\textrm{ (sys.)}$, evolving to $5.1\pm0.3\textrm{ (stat.)} \pm 0.1\textrm{ (sys.)}$ beyond $5{\times} 10^{19}$ eV, while no significant dependence of spectral features on the declination is seen in the accessible range. These features of the spectrum can be reproduced in models with energy-dependent mass composition. The energy density in cosmic rays above $5{\times} 10^{18}$ eV is $(5.66 \pm 0.03 \textrm{ (stat.)} \pm 1.40 \textrm{ (sys.)} ) {\times} 10^{53}~$erg Mpc$^{-3}$.

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The Pierre Auger Collaboration, A. Aab, P. Abreu, M. Aglietta, J. M. Albury, I. Allekotte, A. Almela, J. Alvarez Castillo, J. Alvarez-Muñiz, R. Alves Batista, G. A. Anastasi, L. Anchordoqui, B. Andrada, S. Andringa, C. Aramo, P. R. Araújo Ferreira, H. Asorey, P. Assis, G. Avila, A. M. Badescu, A. Bakalova, A. Balaceanu, F. Barbato, R. J. Barreira Luz, K. H. Becker, J. A. Bellido, C. Berat, M. E. Bertaina, X. Bertou, P. L. Biermann, T. Bister, J. Biteau, A. Blanco, J. Blazek, C. Bleve, M. Boháčová, D. Boncioli, C. Bonifazi, L. Bonneau Arbeletche, N. Borodai, A. M. Botti, J. Brack, T. Bretz, F. L. Briechle, P. Buchholz, A. Bueno, S. Buitink, M. Buscemi, K. S. Caballero-Mora, L. Caccianiga, L. Calcagni, A. Cancio, F. Canfora, I. Caracas, J. M. Carceller, R. Caruso, A. Castellina, F. Catalani, G. Cataldi, L. Cazon, M. Cerda, J. A. Chinellato, K. Choi, J. Chudoba, L. Chytka, R. W. Clay, A. C. Cobos Cerutti, R. Colalillo, A. Coleman, M. R. Coluccia, R. Conceição, A. Condorelli, G. Consolati, F. Contreras, F. Convenga, C. E. Covault, S. Dasso, K. Daumiller, B. R. Dawson, J. A. Day, R. M. de Almeida, J. de Jesús, S. J. de Jong, G. De Mauro, J. R. T. de Mello Neto, I. De Mitri, J. de Oliveira, D. de Oliveira Franco, V. de Souza, E. De Vito, J. Debatin, M. del Río, O. Deligny, H. Dembinski, N. Dhital, C. Di Giulio, A. Di Matteo, M. L. Díaz Castro, C. Dobrigkeit, J. C. D'Olivo. 2020-08-14. Features of the energy spectrum of cosmic rays above $2.5{\times} 10^{18}$ eV using the Pierre Auger Observatory. https://doi.org/10.1103/physrevlett.125.121106

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