Ponente
Descripción
The cosmic ray knee, observed at around 4 PeV, marks a striking feature in the all-particle cosmic ray spectrum and is widely regarded as the signature of the end of the Galactic component. Recent direct measurements from DAMPE, CALET, and ISS-CREAM are now probing the spectrum with unprecedented precision up to the vicinity of the knee, while LHAASO has provided groundbreaking indirect data on both the all-particle flux and composition in this critical energy range. These advances are challenging the traditional view that the knee reflects either the maximum acceleration energy of Galactic sources or a change in diffusion properties of the Galactic magnetic field. Surprisingly, when considered together, these new observations indicate a breakdown of the standard rigidity paradigm, suggesting either the emergence of a new population of cosmic ray sources at the highest energies or the need for additional physical mechanisms. In this talk, I will discuss recent developments and present novel interpretations of the data, exploring how these results reshape our understanding of the Galactic–extragalactic transition and the origin of the highest energy Galactic cosmic rays.
