Abstract
We test the predictions of hadronic interaction models regarding the depth of maximum of air-shower profiles, Xmax, and ground-particle signals in water-Cherenkov detectors at 1000 m from the shower core, S(1000), using the data from the fluorescence and surface detectors of the Pierre Auger Observatory. The test consists of fitting the measured two-dimensional (S(1000), Xmax) distributions using templates for simulated air showers produced with hadronic interaction models epos-lhc, qgsjet-ii-04, sibyll 2.3d and leaving the scales of predicted Xmax and the signals from hadronic component at ground as free-fit parameters. The method relies on the assumption that the mass composition remains the same at all zenith angles, while the longitudinal shower development and attenuation of ground signal depend on the mass composition in a correlated way. The analysis was applied to 2239 events detected by both the fluorescence and surface detectors of the Pierre Auger Observatory with energies between 1018.5 eV to 1019.0 eV and zenith angles below 60°. We found, that within the assumptions of the method, the best description of the data is achieved if the predictions of the hadronic interaction models are shifted to deeper Xmax values and larger hadronic signals at all zenith angles. Given the magnitude of the shifts and the data sample size, the statistical significance of the improvement of data description using the modifications considered in the paper is larger than 5σ even for any linear combination of experimental systematic uncertainties.
| Original language | English |
|---|---|
| Article number | 102001 |
| Number of pages | 28 |
| Journal | Physical Review D |
| Volume | 109 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - 15 May 2024 |
Bibliographical note
Funding Information:The successful installation, commissioning, and operation of the Pierre Auger Observatory would not have been possible without the strong commitment and effort from the technical and administrative staff in Malarg\u00FCe. We are very grateful to the following agencies and organizations for financial support. Argentina\u2014Comisi\u00F3n Nacional de Energ\u00EDa At\u00F3mica; Agencia Nacional de Promoci\u00F3n Cient\u00EDfica y Tecnol\u00F3gica (ANPCyT); Consejo Nacional de Investigaciones Cient\u00EDficas y T\u00E9cnicas (CONICET); Gobierno de la Provincia de Mendoza; Municipalidad de Malarg\u00FCe; NDM Holdings and Valle Las Le\u00F1as; in gratitude for their continuing cooperation over land access; Australia\u2014the Australian Research Council; Belgium\u2014Fonds de la Recherche Scientifique (FNRS); Research Foundation Flanders (FWO), Marie Curie Action of the European Union Grant No. 101107047; Brazil\u2014Conselho Nacional de Desenvolvimento Cient\u00EDfico e Tecnol\u00F3gico (CNPq); Financiadora de Estudos e Projetos (FINEP); Funda\u00E7\u00E3o de Amparo \u00E0 Pesquisa do Estado de Rio de Janeiro (FAPERJ); S\u00E3o Paulo Research Foundation (FAPESP) Grants No. 2019/10151-2, No. 2010/07359-6, and No. 1999/05404-3; Minist\u00E9rio da Ci\u00EAncia, Tecnologia, Inova\u00E7\u00F5es e Comunica\u00E7\u00F5es (MCTIC); Czech Republic\u2014No. GACR 24-13049S, No. CAS LQ100102401, No. MEYS LM2023032, No. CZ.02.1.01/0.0/0.0/16_013/0001402, No. CZ.02.1.01/0.0/0.0/18_046/0016010, No. CZ.02.1.01/0.0/0.0/17_049/0008422 and No. CZ.02.01.01/00/22_008/0004632; France\u2014Centre de Calcul IN2P3/CNRS; Centre National de la Recherche Scientifique (CNRS); Conseil R\u00E9gional Ile-de-France; D\u00E9partement Physique Nucl\u00E9aire et Corpusculaire (PNC-IN2P3/CNRS); D\u00E9partement Sciences de l\u2019Univers (SDU-INSU/CNRS); Institut Lagrange de Paris (ILP) Grant No. LABEX ANR-10-LABX-63 within the Investissements d\u2019Avenir Programme Grant No. ANR-11-IDEX-0004-02; Germany\u2014Bundesministerium f\u00FCr Bildung und Forschung (BMBF); Deutsche Forschungsgemeinschaft (DFG); Finanzministerium Baden-W\u00FCrttemberg; Helmholtz Alliance for Astroparticle Physics (HAP); Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF); Ministerium f\u00FCr Kultur und Wissenschaft des Landes Nordrhein-Westfalen; Ministerium f\u00FCr Wissenschaft, Forschung und Kunst des Landes Baden-W\u00FCrttemberg; Italy\u2014Istituto Nazionale di Fisica Nucleare (INFN); Istituto Nazionale di Astrofisica (INAF); Ministero dell\u2019Universit\u00E0 e della Ricerca (MUR); CETEMPS Center of Excellence; Ministero degli Affari Esteri (MAE), ICSC Centro Nazionale di Ricerca in High Performance Computing, Big Data and Quantum Computing, funded by European Union NextGenerationEU, reference code CN_00000013; M\u00E9xico\u2014Consejo Nacional de Ciencia y Tecnolog\u00EDa (CONACYT) No. 167733; Universidad Nacional Aut\u00F3noma de M\u00E9xico (UNAM); PAPIIT DGAPA-UNAM; The Netherlands\u2014Ministry of Education, Culture and Science; Netherlands Organisation for Scientific Research (NWO); Dutch national e-infrastructure with the support of SURF Cooperative; Poland\u2014Ministry of Education and Science, grants No. DIR/WK/2018/11 and 2022/WK/12; National Science Centre, Grants No. 2016/22/M/ST9/00198, No. 2016/23/B/ST9/01635, No. 2020/39/B/ST9/01398, and No. 2022/45/B/ST9/02163; Portugal\u2014Portuguese national funds and FEDER funds within Programa Operacional Factores de Competitividade through Funda\u00E7\u00E3o para a Ci\u00EAncia e a Tecnologia (COMPETE); Romania\u2014Ministry of Research, Innovation and Digitization, CNCS-UEFISCDI, Contract No. 30N/2023 under Romanian National Core Program LAPLAS VII, Grant No. PN 23 21 01 02 and Project No. PN-III-P1-1.1-TE-2021-0924/TE57/2022, within PNCDI III; Slovenia\u2014Slovenian Research Agency, Grants No. P1-0031, No. P1-0385, No. I0-0033, No. N1-0111; Spain\u2014Ministerio de Econom\u00EDa, Industria y Competitividad (FPA2017-85114-P and PID2019\u2013104676 GB-C32), Xunta de Galicia (ED431C 2017/07), Junta de Andaluc\u00EDa (SOMM17/6104/UGR, P18-FR-4314) Feder Funds, RENATA Red Nacional Tem\u00E1tica de Astropart\u00EDculas (FPA2015-68783-REDT) and Mar\u00EDa de Maeztu Unit of Excellence (MDM-2016-0692); USA\u2014Department of Energy, Contracts No. DE-AC02-07CH11359, No. DE-FR02-04ER41300, No. DE-FG02-99ER41107, and No. DE-SC0011689; National Science Foundation, Grant No. 0450696; The Grainger Foundation; Marie Curie-IRSES/EPLANET; European Particle Physics Latin American Network; and UNESCO.
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