From left to right: Demonstration of our synthetic imaging pipeline. All panels show a 2D slice through our 3D jet simulations. The pipeline starts to extract the particle population from the underlying fluid (see Fig. 3). The particle population in panel (a) is color-coded by dimensionless averaged particle energy. Brighter colors (white and yellow) represent higher energies, i.e., the case for the inner jet spine. The recollimation shock, associated with a centralized region of higher energy, is visible in the jet’s spine. The particles are “cooled” by radiative losses (orange and red) and cool even more rapidly when leaving the jet flow. Panels (b)–(d) illustrate the interpolated particle values that form a grid of particle attributes (highest values in red): Panel (b) shows a 3D grid of the spectral index, α, calculated from the spectrum’s slope, s, of the energetic changes due to radiative losses at a given frequency. Panel (c) highlights the lower energy cutoff, γ_min, of the particle’s energy distribution. Panel (d) shows the calculated normalization constant, N_e, of the energy distribution interpolated onto a 3D grid.