Searching for EeV photons with Telescope Array Surface Detector and neural networks
Telescope Array Collaboration, R. U. Abbasi (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), T. Abu-Zayyad (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), M. Allen (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), J. W. Belz (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), D. R. Bergman (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), F. Bradfield (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), I. Buckland (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), W. Campbell (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), B. G. Cheon (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), K. Endo (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), A. Fedynitch (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), T. Fujii (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), K. Fujisue (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), K. Fujita (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), M. Fukushima (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), G. Furlich (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), A. Galvez Urena (CEICO, Institute of Physics, Czech Academy of Sciences, Prague 182 21, Czech Republic), Z. Gerber (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), N. Globus (Institute of Astronomy, National Autonomous University of Mexico Ensenada Campus, Ensenada, BC 22860, Mexico), T. Hanaoka (Graduate School of Engineering, Osaka Electro-Communication University, Neyagawa-shi, Osaka 572-8530, Japan), W. Hanlon (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), N. Hayashida (Faculty of Engineering, Kanagawa University, Yokohama, Kanagawa 221-8686, Japan), H. He (Astrophysical Big Bang Laboratory, RIKEN, Wako, Saitama 351-0198, Japan), K. Hibino (Faculty of Engineering, Kanagawa University, Yokohama, Kanagawa 221-8686, Japan), R. Higuchi (Astrophysical Big Bang Laboratory, RIKEN, Wako, Saitama 351-0198, Japan), D. Ikeda (Faculty of Engineering, Kanagawa University, Yokohama, Kanagawa 221-8686, Japan), D. Ivanov (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), S. Jeong (Department of Physics, Sungkyunkwan University, Jang-an-gu, Suwon 16419, Korea), C. C. H. Jui (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), K. Kadota (Department of Physics, Tokyo City University, Setagaya-ku, Tokyo 158-8557, Japan), F. Kakimoto (Faculty of Engineering, Kanagawa University, Yokohama, Kanagawa 221-8686, Japan), O. Kalashev (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia), K. Kasahara (Faculty of Systems Engineering and Science, Shibaura Institute of Technology, Minumaku, Tokyo 337-8570, Japan), Y. Kawachi (Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan), K. Kawata (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), I. Kharuk (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia), E. Kido (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), H. B. Kim (Department of Physics and The Research Institute of Natural Science, Hanyang University, Seongdong-gu, Seoul 426-791, Korea), J. H. Kim (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), J. H. Kim (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), S. W. Kim (Department of Physics, Sungkyunkwan University, Jang-an-gu, Suwon 16419, Korea), R. Kobo (Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan), I. Komae (Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan), K. Komatsu (Academic Assembly School of Science and Technology Institute of Engineering, Shinshu University, Nagano, Nagano 380-8554, Japan), K. Komori (Graduate School of Engineering, Osaka Electro-Communication University, Neyagawa-shi, Osaka 572-8530, Japan), A. Korochkin (Service de Physique Theorique, Universite Libre de Bruxelles, Brussels 1050, Belgium), C. Koyama (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), M. Kudenko (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia), M. Kuroiwa (Academic Assembly School of Science and Technology Institute of Engineering, Shinshu University, Nagano, Nagano 380-8554, Japan), Y. Kusumori (Graduate School of Engineering, Osaka Electro-Communication University, Neyagawa-shi, Osaka 572-8530, Japan), M. Kuznetsov (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia), Y. J. Kwon (Department of Physics, Yonsei University, Seodaemun-gu, Seoul 120-749, Korea), K. H. Lee (Department of Physics and The Research Institute of Natural Science, Hanyang University, Seongdong-gu, Seoul 426-791, Korea), M. J. Lee (Department of Physics, Sungkyunkwan University, Jang-an-gu, Suwon 16419, Korea), B. Lubsandorzhiev (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia), J. P. Lundquist (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA, Center for Astrophysics and Cosmology, University of Nova Gorica, Nova Gorica 5297, Slovenia), H. Matsushita (Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan), A. Matsuzawa (Academic Assembly School of Science and Technology Institute of Engineering, Shinshu University, Nagano, Nagano 380-8554, Japan), J. A. Matthews (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), J. N. Matthews (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), K. Mizuno (Academic Assembly School of Science and Technology Institute of Engineering, Shinshu University, Nagano, Nagano 380-8554, Japan), M. Mori (Graduate School of Engineering, Osaka Electro-Communication University, Neyagawa-shi, Osaka 572-8530, Japan), S. Nagataki (Astrophysical Big Bang Laboratory, RIKEN, Wako, Saitama 351-0198, Japan), K. Nakagawa (Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan), M. Nakahara (Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan), H. Nakamura (Graduate School of Engineering, Osaka Electro-Communication University, Neyagawa-shi, Osaka 572-8530, Japan), T. Nakamura (Faculty of Science, Kochi University, Kochi, Kochi 780-8520, Japan), T. Nakayama (Academic Assembly School of Science and Technology Institute of Engineering, Shinshu University, Nagano, Nagano 380-8554, Japan), Y. Nakayama (Graduate School of Engineering, Osaka Electro-Communication University, Neyagawa-shi, Osaka 572-8530, Japan), K. Nakazawa (Graduate School of Engineering, Osaka Electro-Communication University, Neyagawa-shi, Osaka 572-8530, Japan), T. Nonaka (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), S. Ogio (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), H. Ohoka (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), N. Okazaki (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), M. Onishi (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), A. Oshima (College of Science and Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan), H. Oshima (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), S. Ozawa (Quantum ICT Advanced Development Center, National Institute for Information and Communications Technology, Koganei, Tokyo 184-8795, Japan), I. H. Park (Department of Physics, Sungkyunkwan University, Jang-an-gu, Suwon 16419, Korea), K. Y. Park (Department of Physics and The Research Institute of Natural Science, Hanyang University, Seongdong-gu, Seoul 426-791, Korea), M. Potts (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), M. Przybylak (Doctoral School of Exact and Natural Sciences, University of Lodz, Lodz, Lodz 90-237, Poland), M. S. Pshirkov (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia, Sternberg Astronomical Institute, Moscow M.V. Lomonosov State University, Moscow 119991, Russia), J. Remington (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), C. Rott (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), G. I. Rubtsov (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia), D. Ryu (Department of Physics, School of Natural Sciences, Ulsan National Institute of Science and Technology, UNIST-gil, Ulsan 689-798, Korea), H. Sagawa (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), N. Sakaki (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), R. Sakamoto (Graduate School of Engineering, Osaka Electro-Communication University, Neyagawa-shi, Osaka 572-8530, Japan), T. Sako (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), N. Sakurai (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), S. Sakurai (Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan), D. Sato (Academic Assembly School of Science and Technology Institute of Engineering, Shinshu University, Nagano, Nagano 380-8554, Japan), K. Sekino (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), T. Shibata (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), J. Shikita (Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan), H. Shimodaira (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), H. S. Shin (Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan, Nambu Yoichiro Institute of Theoretical and Experimental Physics, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan), K. Shinozaki (Astrophysics Division, National Centre for Nuclear Research, Warsaw 02-093, Poland), J. D. Smith (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), P. Sokolsky (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), B. T. Stokes (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), T. A. Stroman (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), H. Tachibana (Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan), K. Takahashi (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), M. Takeda (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), R. Takeishi (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), A. Taketa (Earthquake Research Institute, University of Tokyo, Bunkyo-ku, Tokyo 277-8582, Japan), M. Takita (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan), Y. Tameda (Graduate School of Engineering, Osaka Electro-Communication University, Neyagawa-shi, Osaka 572-8530, Japan), K. Tanaka (Graduate School of Information Sciences, Hiroshima City University, Hiroshima, Hiroshima 731-3194, Japan), M. Tanaka (Institute of Particle and Nuclear Studies, KEK, Tsukuba, Ibaraki 305-0801, Japan), M. Teramoto (Graduate School of Engineering, Osaka Electro-Communication University, Neyagawa-shi, Osaka 572-8530, Japan), S. B. Thomas (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), G. B. Thomson (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), P. Tinyakov (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia, Service de Physique Theorique, Universite Libre de Bruxelles, Brussels 1050, Belgium), I. Tkachev (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia), T. Tomida (Academic Assembly School of Science and Technology Institute of Engineering, Shinshu University, Nagano, Nagano 380-8554, Japan), S. Troitsky (Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia), Y. Tsunesada (Graduate School of Science, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan, Nambu Yoichiro Institute of Theoretical and Experimental Physics, Osaka Metropolitan University, Sugimoto, Sumiyoshi, Osaka 558-8585, Japan), S. Udo (Faculty of Engineering, Kanagawa University, Yokohama, Kanagawa 221-8686, Japan), F. R. Urban (CEICO, Institute of Physics, Czech Academy of Sciences, Prague 182 21, Czech Republic), M. Vrabel (Astrophysics Division, National Centre for Nuclear Research, Warsaw 02-093, Poland), D. Warren (Astrophysical Big Bang Laboratory, RIKEN, Wako, Saitama 351-0198, Japan), K. Yamazaki (College of Science and Engineering, Chubu University, Kasugai, Aichi 487-8501, Japan), Y. Zhezher (Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582, Japan, Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312, Russia), Z. Zundel (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA), J. Zvirzdin (High Energy Astrophysics Institute and Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112-0830, USA)
arXiv:2512.01638v2 Announce Type: replace
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 $Phi_gamma(E_gamma > 10^{19} text{eV}) 10^{20} text{eV}) arXiv:2512.01638v2 Announce Type: replace
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 $Phi_gamma(E_gamma > 10^{19} text{eV}) 10^{20} text{eV})

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