Search for the Anomalous Events Detected by ANITA Using 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, Instituto Galego de Física de Altas Enerxías (IGFAE)
J. Ammerman Yebra, Instituto Galego de Física de Altas Enerxías (IGFAE)
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

3-28-2025

Abstract

A dedicated search for upward-going air showers at zenith angles exceeding 110° and energies E>0.1 EeV has been performed using the Fluorescence Detector of the Pierre Auger Observatory. The search is motivated by two "anomalous"radio pulses observed by the ANITA flights I and III that appear inconsistent with the standard model of particle physics. Using simulations of both regular cosmic-ray showers and upward-going events, a selection procedure has been defined to separate potential upward-going candidate events and the corresponding exposure has been calculated in the energy range [0.1-33] EeV. One event has been found in the search period between January 1, 2004, and December 31, 2018, consistent with an expected background of 0.27±0.12 events from misreconstructed cosmic-ray showers. This translates to an upper bound on the integral flux of (7.2±0.2)×10-21 cm-2 sr-1 y-1 and (3.6±0.2)×10-20 cm-2 sr-1 y-1 for an E-1 and E-2 spectrum, respectively. An upward-going flux of showers normalized to the ANITA observations is shown to predict over 34 events for an E-3 spectrum and over 8.1 events for a conservative E-5 spectrum, in strong disagreement with the interpretation of the anomalous events as upward-going showers.

Publication Title

Physical Review Letters

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