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arXiv · 2404.14541

Loss of coherence and change in emission physics for radio emission from very inclined cosmic-ray air showers

Simon Chiche·Chao Zhang·Felix Schlüter·Kumiko Kotera·Tim Huege·Krijn D. de Vries·Matias Tueros·Marion Guelfand
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Abstract

Next-generation radio experiments such as the Radio Detector of the upgraded Pierre Auger Observatory and the planned GRAND and BEACON arrays target the detection of ultra-high-energy particle air showers arriving at low elevation angles. These inclined cosmic-ray air showers develop higher in the atmosphere than vertical ones, enhancing magnetic deflections of electrons and positrons inside the cascade. We evidence two novel features in their radio emission: a new polarization pattern, consistent with a geo-synchrotron emission model and a coherence loss of the radio emission, both for showers with zenith angle $\theta \gtrsim 65^{\circ}$ and strong enough magnetic field amplitude (typical strength of $B\sim 50\, \rm \mu T$). Our model is compared with both ZHAireS and CoREAS Monte-Carlo simulations. Our results break the cannonical description of a radio signal made of Askaryan and transverse current emission only, and provide guidelines for the detection and reconstruction strategies of next-generation experiments, including cosmic-ray/neutrino discrimination.

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Simon Chiche, Chao Zhang, Felix Schlüter, Kumiko Kotera, Tim Huege, Krijn D. de Vries, Matias Tueros, Marion Guelfand. 2024-04-22. Loss of coherence and change in emission physics for radio emission from very inclined cosmic-ray air showers. https://arxiv.org/abs/2404.14541

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