A Search for Photons with Energies Above 2 × 1017 eV Using Hybrid Data from the Low-Energy Extensions of the Pierre Auger Observatory

• Published in: The Astrophysical journal 2022-07, Vol.933 (2), p.125
• Main Authors: Cheminant, K. Almeida, Alvarez-Muñiz, J., Anchordoqui, L., Andrada, B., Aramo, C., Assis, P., Barbato, F., Biermann, P. L., Boncioli, D., Buchholz, P., Bueno, A., Büsken, M., Canfora, F., Caracas, I., Cerda, M., Chudoba, J., Cerutti, A. C. Cobos, Coluccia, M. R., Conceição, R., dos Santos, D. Correia, De Mitri, I., de Oliveira Franco, D., de Palma, F., Deligny, O., Deval, L., Mendes, L. M. Domingues, Dova, M. T., Engel, R., Erdmann, M., Etchegoyen, A., Falcke, H., Farmer, J., Farrar, G., Fauth, A. C., Fazzini, N., Gesualdi, F., Gobbi, F., Berisso, M. Gómez, Vitale, P. F. Gómez, González, N., Gorgi, A., Gottowik, M., Guarino, F., Hampel, M. R., Kunka, N., Lago, B. L., Langner, N., de Oliveira, M. A. Leigui, Lopes, L., López, R., Lundquist, J. P., Manning, B. C., Mariazzi, A. G., Mariş, I. C., Marsella, G., Mathes, H. J., Mayotte, E., Mazur, P. O., Michal, S., Micheletti, M. I., Miramonti, L., Nosek, D., Núñez, L. A., Parra, A., Pawlowsky, J., Peña-Rodriguez, J., Martins, E. E. Pereira, Armand, J. Perez, Perrone, L., Petrera, S., Privitera, P., Roulet, E., Salina, G., Sánchez, F., Santos, E., Sarmento, R., Savina, P., Scherini, V., Schieler, H., Scholten, O., Schovánek, P., Sehgal, S., Shellard, R. C., Smau, R., Squartini, R., Stanca, D., Stanič, S., Suomijärvi, T., Tomé, B., Tueros, M., Unger, M., Galicia, J. F. Valdés, Valore, L., Verzi, V., Wahlberg, H., Watanabe, C., Watson, A. A., Weindl, A., Zas, E., Zavrtanik, M.
• Format: Article
• Language: English
• Subjects: Astronomy; ASTRONOMY AND ASTROPHYSICS; Astrophysics; Augers; Cosmic ray showers; Cosmic rays; Energy; Gamma rays; High energy astronomy; Multivariate analysis; Neutrinos; Non-thermal radiation sources; Particle astrophysics; Photons; Ultra-high-energy cosmic radiation
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ac7393

Ultra-high-energy photons with energies exceeding 1017 eV offer a wealth of connections to different aspects of cosmic-ray astrophysics as well as to gamma-ray and neutrino astronomy. The recent observations of photons with energies in the 1015 eV range further motivate searches for even higher-energy photons. In this paper, we present a search for photons with energies exceeding 2 × 1017 eV using about 5.5 yr of hybrid data from the low-energy extensions of the Pierre Auger Observatory. The upper limits on the integral photon flux derived here are the most stringent ones to date in the energy region between 1017 and 1018 eV.