Highlights from the Pierre Auger Observatory (ICRC17)

TL;DR

This paper summarizes key findings from the Pierre Auger Observatory, including cosmic ray spectrum measurements, composition studies, anisotropy discoveries, and progress on detector upgrades to understand ultra-high-energy cosmic rays.

Contribution

It provides an updated overview of cosmic ray observations, anisotropy detections, and the development of the AugerPrime upgrade for better understanding of cosmic ray origins.

Findings

Measurement of cosmic ray energy spectrum from 10^{17.5} to above 10^{20} eV

Detection of large-scale anisotropy above 8×10^{18} eV

Progress in the AugerPrime upgrade for improved composition analysis

Abstract

In this contribution we summarize the highlights from the Pierre Auger Observatory presented at the 35th International Cosmic Ray Conference. We discuss the update of the measurement of the energy spectrum of cosmic rays over a wide range of energy ($10^{17.5}$ to above $10^{20}$ eV), studies of the cosmic-ray mass composition with the fluorescence and surface detector of the Observatory, the discovery of a large-scale anisotropy in the arrival direction of cosmic rays above $8\times 10^{18}$ eV and indications of anisotropy at intermediate angular scales above $4 \times 10^{19}$ eV. Moreover, we report on tests of hadronic interactions beyond LHC energies, multi-messenger analyses with neutral primaries and the progress of the upgrade of the Observatory, AugerPrime, aimed at elucidating the origin of the observed flux suppression at ultra-high energies.