Speaker
Description
Latest measurements of spectra of different cosmic ray elements at TeV–PeV energies, as well as the all-particle spectrum and mean logarithmic mass, provide a wealth of new information for models of Galactic cosmic ray acceleration and propagation. At the same time, a consistent interpretation of all available datasets remains challenging, and different theoretical frameworks are often not readily distinguishable in the data. In light of this, we seek to build a minimal phenomenological model that self-consistently explains all observables in the chosen energy range as measured by the relevant experiments. The model is built on basic physical assumptions: power-law injection spectra, modified during propagation in a rigidity-dependent way. We perform a global fit to all available datasets, accounting for energy-scale uncertainties and consistency between elemental and all-particle measurements. We show conclusively that the data cannot be adequately described by a single-population model, in which all observed spectral features are attributed to propagation effects, even without including the latest LHAASO measurements of proton and helium spectra. A two-population model emerges as the next minimal alternative, featuring one population with lower maximum energy that provides the bulk of the CR energy density (SNR-like), and a second population of more energetic but rarer sources (e.g., microquasar-like). The hardening of elemental spectra around ~150 TV is produced by the interplay between the two populations. The softenings at ~13 TV and ~3 PV (the knee) are instead interpreted as genuine breaks in populations’ spectra, arising either from propagation effects or from maximum acceleration energies.
