Karlsruhe 2024 – scientific programme

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T: Fachverband Teilchenphysik

T 9: Cosmic rays 2

T 9.7: Talk

Monday, March 4, 2024, 17:30–17:45, Geb. 30.22: Lehmann-HS

Updating the hybrid search for photons with the low-energy extensions of the Pierre Auger Observatory* — •Tim Fehler, Marcus Niechciol, and Markus Risse for the Pierre-Auger collaboration — Experimentelle Astroteilchenphysik, Center for Particle Physics Siegen, Universität Siegen

Ultra-high-energy (UHE) photons can reliably be detected with air-shower arrays, which have been primarily designed to efficiently observe cosmic rays at the highest energies. The diverse detector systems of the Pierre Auger Observatory have been utilized to place stringent upper limits on the diffuse, i.e. the direction-independent, unresolved, integral flux of UHE photons across several orders of magnitude in energy. A key focus has been on pushing the energy threshold of these analyses down to 10¹⁷ eV and below, as this energy range offers numerous connections to various aspects of multimessenger astrophysics. Currently, upper limits down to a threshold of 2 × 10¹⁷ eV have been determined using the low-energy extensions of the Observatory, namely the high-elevation fluorescence telescopes and the sub-array of the surface detector with spacing of 750 m. This contribution details the ongoing studies, based on simulations, to update this analysis and optimize the search strategy. The aim is to leverage the full Phase-1 dataset, which would more than double the statistics compared to the last publication in 2022.

*Supported by the BMBF Verbundforschung Astroteilchenphysik

Keywords: UHE photons; extensive air showers; simulations