Astronomical observations through the new 100 TeV gamma-ray observational window by HAWC, Tibet  and LHAASO air shower arrays, and, in the near future, by the Cherenkov Telescope Array CTA open a range of completely new possibilities for the study of highest energy galactic cosmic ray sources. These sources, dubbed "PeVatrons" (yet to be identified) produce particles with energies in excess of Peta-electronVolt, three orders of magnitude higher than those attained in the most powerful human-made accelerator LHC.  Those sources are responsible for flux of multi-PeV cosmic rays penetrating in the Earth atmosphere  and  are perhaps responsible for Galactic part of astrophysical neutrino signal, observed by the IceCube neutrino telescope.   

The goal of STAGE and THESIS will be to develop a realistic numerical model of anisotropic diffusion of cosmic rays from their PeVatron sources through  the magnetic field of the Milky Way galaxy and to supplement this model with a model of cosmic ray interactions with interstellar gas that leads to production of gamma rays and neutrinos. This numerical model will be constrained by the observational data on cosmic rays, gamma-rays and neutrinos. The model will be ultimately used in analysis of the multi-messenger astronomical data: TALE, IceTop and LHAASO data for cosmic rays, HESS, Fermi, HAWC, Tibet, LHAASO and CTA gamma-ray data as well as ICECUBE, KM3NeT and Baikal-GVD neutrino telescope data.