Speaker
Description
Ultra-high-energy cosmic rays (UHECRs) are the most energetic particles known - and yet their origin is still an open question. However, with the precision and accumulated statistics of the Pierre Auger Observatory and the Telescope Array, in combination with advancements in theory and modeling - especially of the Galactic magnetic field - it is now possible to set solid constraints on the sources of UHECRs. The spectrum and composition measurements above the ankle can be well described by a population of extragalactic, homogeneously distributed sources. Using additionally the observed anisotropy in the arrival directions, namely the large-scale anisotropies as well as smaller-scale warmspots at higher energies, even more powerful constraints on the source density as well as the contribution of individual sources can be placed. However, these findings raise further questions, for example whether sources are transient or continuous or why sources are required to be strikingly similar to explain the measurements. The current findings and possible interpretation of UHECR data will be presented in this review.
