Momentum- and synchrotron spectrum of an arbitrarily chosen SPH particle with an active CR electron population. We show the spectra at every second available output time between z = 1 and z = 0 in the COMA simulation. Left: Momentum spectrum of the electron population in the momentum range relevant for synchrotron emission. Dashed lines indicate the momentum bin boundaries imposed in our CR scheme. Right: The resulting synchrotron emissivity spectrum of the same electron population.