Testing hadronic-model predictions of depth of maximum of air-shower profiles and ground-particle signals using hybrid data of the Pierre Auger Observatory

Authors

A. Abdul Halim, The University of Adelaide
P. Abreu, Instituto Superior Técnico
M. Aglietta, Istituto Nazionale di Fisica Nucleare, Sezione di Torino
I. Allekotte, Centro Atomico Bariloche
K. Almeida Cheminant, Henryk Niewodniczanski Institute of Nuclear Physics of the Polish Academy of Sciences
A. Almela, Comision Nacional de Energia Atomica Argentina
R. Aloisio, Gran Sasso Science Institute
J. Alvarez-Muñiz, Universidad de Santiago de Compostela
J. Ammerman Yebra, Universidad de Santiago de Compostela
G. A. Anastasi, Istituto Nazionale di Fisica Nucleare, Sezione di Catania
L. Anchordoqui, Lehman College
B. Andrada, Comision Nacional de Energia Atomica Argentina
S. Andringa, Instituto Superior Técnico
L. Apollonio, Istituto Nazionale di Fisica Nucleare, Sezione di Milano
C. Aramo, Istituto Nazionale di Fisica Nucleare, Sezione di Napoli
P. R. Araújo Ferreira, Rheinisch-Westfälische Technische Hochschule Aachen
E. Arnone, Istituto Nazionale di Fisica Nucleare, Sezione di Torino
J. C. Arteaga Velázquez, Universidad Michoacana de San Nicolás de Hidalgo
P. Assis, Instituto Superior Técnico
G. Avila, Comision Nacional de Energia Atomica Argentina
E. Avocone, Laboratori Nazionali del Gran Sasso
A. Bakalova, Institute of Physics of the Czech Academy of Sciences
F. Barbato, Gran Sasso Science Institute
A. Bartz Mocellin, Colorado School of Mines
J. A. Bellido, The University of Adelaide
C. Berat, Université Grenoble Alpes
M. E. Bertaina, Istituto Nazionale di Fisica Nucleare, Sezione di Torino
G. Bhatta, Henryk Niewodniczanski Institute of Nuclear Physics of the Polish Academy of Sciences
M. Bianciotto, Istituto Nazionale di Fisica Nucleare, Sezione di Torino
P. L. Biermann, Max Planck Institute for Radio Astronomy
V. Binet, Instituto de Fisica Rosario

Document Type

Article

Publication Date

5-15-2024

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.

Publication Title

Physical Review D

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