Gamma rays as cosmic ray tracers: how can CTAO contribute to the cosmic ray physics

Gamma-ray emission produced by interactions of cosmic rays with interstellar matter and radiation fields is a probe of non-thermal particles in galaxies. After decades of instrumental improvements in the field of gamma-ray astronomy, different scales and environments are now accessible and their gamma-ray observations reveal several properties of cosmic rays, especially in our Galaxy. I will provide a short review of the status of the subject and I will also discuss how the next generation of gamma-ray facilities can contribute to the advancement of the topic. In particular, I will focus on the Cherenkov Telescope Array Observatory (CTAO) capabilities. CTAO will be the first proposal-driven observatory in this energy range that will deliver science-ready data to the entire community.