Ultra-high energy cosmic rays represent the most energetic particles available to scientists. These particles have macroscopic energies, exceeding 1 EeV,but their detectionisa challenge, their flux beingvery weak, around one particle per square kilometer per century for the highest energies. The Pierre Auger Observatory, in Argentina, is the present flagship experiment studying ultra-high energy cosmic rays. The combination of a large array of surface detectors covering 3000 km2 and fluorescence telescopes enhances the performances of the extensive air shower detection and measurements, resulting in both high statistics and unprecedented data quality. Moreover, the operation of a denser sub-array has extended the sensitivity to lower energies. Altogether, these well performing detectors contribute to providing important information on key questions on cosmic rays in the energy range from 0.1 EeV up to 100 EeV, as highlighted in this presentation of the latest results obtained by the Pierre Auger Collaboration. Despite a large number of valuable results, the understanding of the nature and the origin of the highest energy cosmic rays remains an open science case that the Auger Collaboration is willing to address with the AugerPrime project.
A search for ultra-high-energy photons at the Pierre Auger Observatory exploiting air-shower universality
