Speaker
Description
Recently, LHAASO has announced the highest-energy measurements of the diffusive gamma-ray flux, offering the possibility of probing the spatial distribution and energy spectrum of the galactic cosmic rays (CRs) up to the all-particle spectrum knee ($\sim 4$ PeV). However, a persistent tension between observations by experiments (such as Fermi and LHAASO) and the predictions based on measurements of the local CR flux increase the necessity of a robust model of the CR spectrum. In the present work, we estimate the gamma-ray flux coming from CRs with energies as high as the knee. We developed a phenomenological model of the galactic CR flux using the latest data available by satellite missions and ground-based observatories. In particular, our model identifies the series of spectral breaks found in the proton and helium fluxes in the range of $10^2$ to $10^7$ GeV and corroborates that these breaks are located at the same rigidity for different CR species. In contrast with other models, our analysis also includes the most recent measurements of the proton spectrum by the GRAPES-3 experiment, showing an additional spectral break at $\sim 160$ TeV. We also include the uncertainty related to the contribution of heavier nuclei in the CR composition. We compare our expected gamma-ray flux with previous models and recent observational data, focusing our discussion on the new spectral features provided by our model.
