Speaker
Olivier Deligny
(CNRS/IN2P3)
Description
The Pierre Auger Observatory, located near the town of Malargüe, Argentina, has been detecting ultra-high energy cosmic rays for more than ten years. An essential feature of the 3,000 km$^2$ Observatory is its hybrid design: cosmic rays above 10$^{17}$ eV are detected through the observation of the associated air showers with different and complementary techniques, from surface detector arrays and fluorescence telescopes to radio antennas. The analyses of the multi-detector data have enabled high-statistics and high-precision studies of the energy spectrum, mass composition and distribution of arrival directions of ultra-high energy cosmic rays (UHECRs), the investigation of whose origin being a primary objective of the Observatory. The data have also enabled us to search for ultra-high energy photons and neutrinos, and to perform a measurement of the proton-air cross section at 57 TeV center-of-mass energy. A coherent interpretation of all these recent results, requiring the use of LHC-tuned interaction models to describe the air showers, opens new directions regarding the properties of UHECR sources. The resulting picture, calling into question the perception of UHECRs at the time of the conception of the Observatory in the early 1990s, has led to a plan for an upgrade of the Observatory. In this talk, I will present the most recent results obtained with the Pierre Auger Observatory, their interpretation, and the motivations for upgrading the Observatory - upgrade which is currently undertaken.
Author
Olivier Deligny
(CNRS/IN2P3)
