A dedicated search for upward-going air showers at zenith angles exceeding 110° and energies 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 events from misreconstructed cosmic-ray showers. This translates to an upper bound on the integral flux of and for an and spectrum, respectively. An upward-going flux of showers normalized to the ANITA observations is shown to predict over 34 events for an spectrum and over 8.1 events for a conservative spectrum, in strong disagreement with the interpretation of the anomalous events as upward-going showers.
Abdul Halim, A., et al. "Search for the Anomalous Events Detected by ANITA Using the Pierre Auger Observatory." Physical Review Letters, vol. 134, no. 12, Mar. 2025. https://doi.org/10.1103/PhysRevLett.134.121003
Abdul Halim, A., Abreu, P., Aglietta, M., Allekotte, I., Almeida Cheminant, K., Almela, A., Aloisio, R., Alvarez-Muñiz, J., Ammerman Yebra, J., Anastasi, G. A., Anchordoqui, L., Andrada, B., Andringa, S., Apollonio, L., Aramo, C., Araújo Ferreira, P. R., Arnone, E., Arteaga Velázquez, J. C., ... Zeolla, A. (2025). Search for the Anomalous Events Detected by ANITA Using the Pierre Auger Observatory. Physical Review Letters, 134(12). https://doi.org/10.1103/PhysRevLett.134.121003
Abdul Halim, A., Abreu, P., Aglietta, M., et al., "Search for the Anomalous Events Detected by ANITA Using the Pierre Auger Observatory," Physical Review Letters 134, no. 12 (2025), https://doi.org/10.1103/PhysRevLett.134.121003
@article{osti_2539960,
author = {Abdul Halim, A. and Abreu, P. and Aglietta, M. and Allekotte, I. and Almeida Cheminant, K. and Almela, A. and Aloisio, R. and Alvarez-Muñiz, J. and Ammerman Yebra, J. and Anastasi, G. A. and others},
title = {Search for the Anomalous Events Detected by ANITA Using the Pierre Auger Observatory},
annote = { 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. Published by the American Physical Society 2025 },
doi = {10.1103/PhysRevLett.134.121003},
url = {https://www.osti.gov/biblio/2539960},
journal = {Physical Review Letters},
issn = {ISSN PRLTAO},
number = {12},
volume = {134},
place = {United States},
publisher = {American Physical Society},
year = {2025},
month = {03}}
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 551, Issue 2-3https://doi.org/10.1016/j.nima.2005.05.068
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 580, Issue 3https://doi.org/10.1016/j.nima.2007.07.010
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 620, Issue 2-3https://doi.org/10.1016/j.nima.2010.04.023
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 798, p. 172-213https://doi.org/10.1016/j.nima.2015.06.058