Radio Measurements of the Depth of Air-Shower Maximum at the Pierre Auger Observatory

Abstract

The Auger Engineering Radio Array (AERA), part of the Pierre Auger Observatory, is currently the largest array of radio antenna stations deployed for the detection of cosmic rays, spanning an area of $17$ km${}^2$ with 153 radio stations. It detects the radio emission of extensive air showers produced by cosmic rays in the $30-80$ MHz band. Here, we report the AERA measurements of the depth of the shower maximum ($X_{\text{max}}$), a probe for mass composition, at cosmic-ray energies between $10^{17.5}$ to $10^{18.8}$ eV, which show agreement with earlier measurements with the fluorescence technique at the Pierre Auger Observatory. We show advancements in the method for radio $X_{\text{max}}$ reconstruction by comparison to dedicated sets of CORSIKA/CoREAS air-shower simulations, including steps of reconstruction-bias identification and correction, which is of particular importance for irregular or sparse radio arrays. Using the largest set of radio air-shower measurements to date, we show the radio $X_{\text{max}}$ resolution as a function of energy, reaching a resolution better than $15$ g cm${}^{-2}$ at the highest energies, demonstrating that radio $X_{\text{max}}$ measurements are competitive with the established high-precision fluorescence technique. In addition, we developed a procedure for performing an extensive data-driven study of systematic uncertainties, including the effects of acceptance bias, reconstruction bias, and the investigation of possible residual biases. These results have been cross-checked with air showers measured independently with both the radio and fluorescence techniques, a setup unique to the Pierre Auger Observatory.

Published version

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Cited by in corpus (9)

• Demonstrating Agreement between Radio and Fluorescence Measurements of the Depth of Maximum of Extensive Air Showers at the Pierre Auger Observatory
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• A LOFAR-style reconstruction of cosmic-ray air showers with SKA-Low
• Aperture correction for Beamforming in radiometric detection of ultra-high energy cosmic rays
• Radio Detection of ultra-high-energy Cosmic-Ray Air Showers
• AI-Enhanced Self-Triggering for Extensive Air Showers: Performance and FPGA Feasibility
• Energy evolution of cosmic-ray mass and intensity measured by the Pierre Auger Observatory
• Uncertainties in the Estimation of Air Shower Observables from Monte Carlo Simulation of Radio Emission
• A Bayesian Method for Air-Shower Reconstruction using Information Field Theory