TALK: What have we learned about ultra-high-energy cosmic rays from the Pierre Auger Observatory?

ABSTRACT: The Pierre Auger Observatory is the largest cosmic-ray detector for the measurement of ultra-high-energy cosmic rays. In this talk, a review of our current understanding of these particles will be given, emphasizing the progress made in recent years thanks to the data collected with the Auger Observatory. A number of unexpected observations has led to a new picture of ultra-high-energy cosmic rays with increasingly strong constraints on the properties of their sources and their interactions in the atmosphere. The talk will conclude with a discussion of the currently ongoing upgrade of the Pierre Auger Observatory, which will address fundamental questions that have emerged from the cosmic-ray observations made so far.