Searching for EeV photons with Telescope Array Surface Detector and neural networks

2025/12/01 by Telescope Array Collaboration, Abbasi, R. U., Abu-Zayyad, T. +126
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #High Energy Physics - Experiment (hep-ex) #Instrumentation and Methods for Astrophysics (astro-ph.IM)

paper · doi:10.48550/arxiv.2512.01638

Abstract

Ultra-high-energy photons play an important role in probing astrophysical models and beyond-Standard-Model scenarios. We report updated limits on the diffuse photon flux using Telescope Array's Surface Detector data collected over 14 years of operation. Our method employs a neural network classifier to effectively distinguish between proton-induced and photon-induced events. The input data include both reconstructed composition-sensitive parameters and raw time-resolved signals registered by the Surface Detector stations. To mitigate biases from Monte Carlo simulations, we fine-tune the network with a subset of experimental data. The number of observed photon candidates is found to be consistent with the expected hadronic background, yielding upper limits on photon flux Φ_γ(E_γ> 10¹⁹ eV) < 2.3 ⋅ 10^-3 , and Φ_γ(E_γ> 10²⁰ eV) < 3.0 ⋅ 10^-4 (km² ⋅ sr ⋅ yr)^-1 .

Citations

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