The Pierre Auger Observatory: Contributions to the 39th International Cosmic Rays Conference (2507.13771v1)

Abstract: The Pierre Auger Observatory, located in La Pampa Amarilla, Argentina, has been continuously acquiring data since 2004. It comprises a surface detector array covering 3,000 km$^2$ and 27 fluorescence telescopes, designed to detect extensive air showers initiated by ultra-high-energy cosmic rays. An upgrade to the Observatory was commissioned in 2024, enhancing the existing water-Cherenkov detectors with additional radio antennas, surface scintillator detectors, and a buried scintillator array. This compilation of contributions to the 39th International Cosmic Ray Conference, held in Geneva, Switzerland (July 15-24, 2025), presents recent results from the Pierre Auger Collaboration, addressing a wide range of fundamental questions in astroparticle physics. The included papers cover measurements of the energy spectrum, mass composition, and arrival directions of ultra-high-energy cosmic rays, investigations of hadronic interactions in extensive air showers, and searches for ultra-high-energy photons and neutrinos. Additional topics include radio detection techniques, solar-related phenomena, and atmospheric events such as ELVES and TGFs. The list also contains first results and performance evaluations of the upgraded detectors, AugerPrime, along with reports on outreach and social engagement initiatives conducted by the Collaboration.