Combined fit above 0.1 EeV to the cosmic-ray spectrum and composition measured with the Pierre Auger Observatory
We fit the cosmic-ray spectrum measured with the Pierre Auger Observatory's surface detectors above an energy of $10^{17}$ eV, along with composition information inferred from the depth of shower maximum measured with its fluorescence detectors above an energy threshold of $10^{17.8}$ eV. We consider astrophysical scenarios with two distinct extragalactic source populations: one dominating the flux above a few EeV, and the other dominating at lower energies, with representative nuclei being injected at the sources with power-law spectra and rigidity-dependent cutoffs. The high-energy population exhibits a hard source injection spectrum and a relatively heavy composition, while the low-energy population exhibits a softer spectrum and a lighter composition. Extending the fit down to the low energies considered here shows the potential to test the energy region towards the Galactic to extragalactic transition with the data of the Pierre Auger Observatory. In particular, the Galactic contribution is expected to be still sizable at the lowest energies considered, and the extragalactic contribution needs to become suppressed for decreasing energies, an effect that could naturally result from a magnetic-horizon-induced suppression.
Authors
- Belén Andrada
- Zbigniew Szadkowski (ORCID: https://orcid.org/0000-0002-2690-9912)
- Bruno L. Lago (ORCID: https://orcid.org/0000-0001-9672-0499)
- Carla Taricco (ORCID: https://orcid.org/0000-0002-0129-5539)
- Giovanni Consolati (ORCID: https://orcid.org/0000-0003-3614-245X)
- Juan Manuel Gonzalez (ORCID: https://orcid.org/0000-0001-9193-0921)
- S. Petrera (ORCID: https://orcid.org/0000-0002-6029-1255)
- T. Pierog (ORCID: https://orcid.org/0000-0002-7472-8710)
- G. Sigl (ORCID: https://orcid.org/0000-0002-4396-645X)
- Mateo Fernandez
- T. Huege (ORCID: https://orcid.org/0000-0002-2783-4772)
- Marta Bianciotto (ORCID: https://orcid.org/0000-0002-9599-3214)
- Nicolas Leal
- Carmina Pérez Bertolli (ORCID: https://orcid.org/0000-0002-9790-5732)
- Carlo Salvattore Cruz Sanchez (ORCID: https://orcid.org/0009-0002-6173-0974)
- Frank Schröder (ORCID: https://orcid.org/0000-0001-8495-7210)
- Gustavo Medina‐Tanco (ORCID: https://orcid.org/0000-0002-3202-319X)
- A. C. Fauth (ORCID: https://orcid.org/0000-0001-7239-0288)
- Enrico Arnone (ORCID: https://orcid.org/0000-0001-6740-5051)
- Enrique Varela (ORCID: https://orcid.org/0000-0003-0715-7513)
- O. Schölten (ORCID: https://orcid.org/0000-0003-3649-1254)
- Olena Tkachenko (ORCID: https://orcid.org/0000-0001-6393-7851)
- Lorenzo Cazon (ORCID: https://orcid.org/0000-0001-6748-8395)
- Pierpaolo Savina (ORCID: https://orcid.org/0000-0001-7670-554X)
- B. R. Dawson (ORCID: https://orcid.org/0000-0002-4271-3055)
- Laura Valore
- A. Haungs (ORCID: https://orcid.org/0000-0002-9638-7574)
- Harm Schoorlemmer (ORCID: https://orcid.org/0000-0002-8999-9249)
- Dalibor Nosek (ORCID: https://orcid.org/0000-0001-6219-200X)
- G. Parente (ORCID: https://orcid.org/0000-0003-2847-0461)
- Paula Gina Isar (ORCID: https://orcid.org/0000-0002-1241-584X)
- Janning Meinert (ORCID: https://orcid.org/0000-0001-7582-3456)
- Emanuele De Vito (ORCID: https://orcid.org/0000-0003-2045-7588)
- Adila Abdul Halim (ORCID: https://orcid.org/0000-0003-1218-1737)
- Gonzalo Rodriguez Fernandez (ORCID: https://orcid.org/0000-0002-4683-230X)
- Jiří Blažek (ORCID: https://orcid.org/0000-0002-5870-8947)
- Therese Paulsen
- Adriel Bartz Mocellin
- Berenika Čermáková
- S. J. de Jong (ORCID: https://orcid.org/0000-0002-3120-3367)
- Alexey Yushkov (ORCID: https://orcid.org/0000-0001-5107-9116)
- K. Daumiller (ORCID: https://orcid.org/0000-0002-0527-4823)
- A. Insolia (ORCID: https://orcid.org/0000-0002-9040-1566)
- Darko Veberič (ORCID: https://orcid.org/0000-0003-2683-1526)
- María Isabel Micheletti (ORCID: https://orcid.org/0000-0002-1063-9938)
- A. Segreto (ORCID: https://orcid.org/0000-0001-7341-6603)
- L. Nellen (ORCID: https://orcid.org/0000-0003-1059-8731)
- Felicia Barbato (ORCID: https://orcid.org/0000-0003-0751-6731)
- Jan Pękala
- Viviana Scherini (ORCID: https://orcid.org/0000-0003-3762-4063)
- Gabriela Nicora (ORCID: https://orcid.org/0000-0001-7504-6423)
- Thomas Fitoussi (ORCID: https://orcid.org/0000-0001-9473-9356)
- Katarína Simkova (ORCID: https://orcid.org/0000-0003-2363-9846)
- R. Caruso (ORCID: https://orcid.org/0000-0003-1622-8731)
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- F. Sarazin (ORCID: https://orcid.org/0000-0001-5614-1986)
- V. Verzi (ORCID: https://orcid.org/0000-0003-2291-9387)
- Luis A. Núñez
- Chaitanya Priyadarshi (ORCID: https://orcid.org/0000-0002-9160-9617)
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- E. Zas (ORCID: https://orcid.org/0000-0002-4430-8117)
- Clara Keiko Oliveira Watanabe
- Roberta Colalillo (ORCID: https://orcid.org/0000-0002-4179-9352)
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- L. Miramonti (ORCID: https://orcid.org/0000-0002-2808-5363)
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- Maximilian Straub
- R. Mussa (ORCID: https://orcid.org/0000-0002-0294-9071)
- Camilla Petrucci
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- Fiona H. Ellwanger
- A. Castellina (ORCID: https://orcid.org/0000-0002-0045-2467)
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- Simone Rossoni
- S. Buitink (ORCID: https://orcid.org/0000-0002-6177-497X)
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- Rukije Uzeiroska
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- Edyvânia Emily Pereira Martins (ORCID: https://orcid.org/0000-0002-1167-8314)
- Fridtjof Feldbusch
- S. Vorobiov (ORCID: https://orcid.org/0000-0001-8679-3424)
- Ezequiel Rodriguez (ORCID: https://orcid.org/0000-0002-2523-1919)
- Alexander Novikov (ORCID: https://orcid.org/0000-0002-1086-7252)
- Varada Varma Kizakke Covilakam
- Emanuele Avocone (ORCID: https://orcid.org/0000-0003-3757-2718)
- Primo F. Gómez Vitale (ORCID: https://orcid.org/0000-0001-9689-2020)
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- Patricia María Hansen
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- Peter Mazur
- Marvin Gottowik
- Stanislav Michal
- Johannes Blümer
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- Antonino Del Popolo
- Danilo Zavrtanik (ORCID: https://orcid.org/0000-0002-4596-1521)
- Ralph Engel
- Julian Rautenberg
- Fernando Gollan
- Luis Miguel Domingues Mendes
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- Lukáš Vaclavek
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- Carlos Hojvat
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- Alberto Etchegoyen
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- Diego Melo
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- Veronika Vašíčková
- Alexandra Fernandes (ORCID: https://orcid.org/0000-0002-9187-4007)
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- Sven Querchfeld
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- Sofia Andringa
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- Luciana Andrade Dourado
- Petr Schovánek (ORCID: https://orcid.org/0000-0002-5344-7645)
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- Matias Jorge Tueros (ORCID: https://orcid.org/0000-0003-1570-1419)
- G. Cataldi (ORCID: https://orcid.org/0000-0001-8066-7718)
- Megha Mogarkar
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- Eric-Teunis de Boone
- Mohamed Ismaiel
- Karolina Syrokvas
- Matteo Tambone
- Pim van Dillen
Publication Details
- Published
- 2025-09-24
- DOI
- https://doi.org/10.22323/1.501.0373
- Primary Topic
- Astrophysics and Cosmic Phenomena
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Strong
- Ministerul Cercetării, Inovării şi Digitalizării
- European Commission
- Deutsche Forschungsgemeinschaft
- Agence Nationale de la Recherche
- Fundação de Amparo à Pesquisa do Estado de São Paulo
- Ministerstvo Školství, Mládeže a Tělovýchovy
- Grantová Agentura České Republiky
- Bundesministerium für Bildung und Forschung
- 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
- Conselho Nacional de Desenvolvimento Científico e Tecnológico
- Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
- Centre National de la Recherche Scientifique
- Financiadora de Estudos e Projetos
- Istituto Nazionale di Astrofisica
- Universidad Nacional Autónoma de México
- Ministério da Ciência, Tecnologia, Inovações e Comunicações
- 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
- Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México
- Institut National de Physique Nucléaire et de Physique des Particules