  Detailed modelling of the spectro-spatial distributions of energetic
electrons and protons in galactic discs and haloes of starburst galaxies (SBGs)
is needed in order to follow their interactions with the magnetized
interstellar medium and radiation fields, determine their radiative yields, and
for estimating their residual spectral densities in intergalactic environments.
We have developed a semi-analytical approach for calculating the particle
spectro-spatial distributions in the disc and halo based on a diffusion model
for particle propagation from acceleration sites in the central SB and disc
regions, including all their relevant interaction modes. Important overall
normalization of our models is based on previous modelling of the Galactic disc
(with the GALPROP code), scaled to the higher star-formations rate in NGC253,
and on spatially resolved radio measurements of the central SB and disc. These
provide the essential input for determining the particle distributions and
their predicted radiative yields in the outer disc and inner halo for a range
of values of the key parameters that affect diffusion rate and energy losses.
Results of our work clearly indicate that quantitative description of
non-thermal emission in SBGs has to be based on modelling of the particle
distributions in the entire disc, not just the central SB region.
