Cosmic rays (CRs) are energetic particles first observed around the Earth with energies ranging from MeV to above 10^20 eV and with approximately isotropic arrival directions. A most remarkable change of the power-law spectral slope occurs around 10^15 eV, the so-called knee of the CR spectrum. Below the knee, the standard paradigm holding since the sixties assumes that the particles originate in the Milky Way, very likely from shock acceleration in supernova remnants, and diffuse on turbulent magnetic fields in a kpc-sized halo encompassing the disk of the Galaxy for durations exceeding several Myr. However, several recent measurements of exquisite precision challenge these standard Galactic cosmic-ray models. In this seminar I will give an overview of the research in the field and focus on two pressing question. Are supernova remnants the only or main sources of Galactic cosmic rays? Are discrepancies between observations and predictions from standard transport models due to missing details or do they require fundamental paradigm changes?
The meeting will be broadcast in zoom: https://unipd.zoom.us/j/83633060648
Speaker details: http://userpages.irap.omp.eu/~ltibaldo/
Elisa Prandini, Michele Doro
