Analysis of radio spectra at ν = 1.4 GHz. The top panel shows the ratio of non-thermal () and thermal emission () as a function of redshift. The gray horizontal line indicates a thermal fraction of 10% which is typically observed in local galaxies. The bottom panel shows the result of a fit of the total radio luminosity (L_ν) and the synchrotron component () to a function f(ν)∝ν^−α_1.4. The fit is performed around ν = 1.4 GHz.