Correlation between the gamma-ray luminosity (﹩{L}_{0.1\mbox{--}100\mathrm{GeV}}﹩) and the SFR, respectively, the FIR luminosity (﹩{L}_{8\mbox{--}1000\mu {\rm{m}}}﹩) of star-forming galaxies. Upper limits on the observable gamma-ray emission by Fermi-LAT (open red symbols; Rojas-Bravo & Araya 2016) are contrasted with gamma-ray detections from star-forming galaxies only (solid black) and with AGN emission (filled red); data are taken from Ackermann et al. (2012), except for NGC 2146 (Tang et al. 2014) and Arp 220 (Griffin et al. 2016; Peng et al. 2016). See the text for details on the FIR-to-SFR conversion. We overplot the emission of our simulated galaxies that only account for advective CR transport (light blue) and simulations in which we additionally follow anisotropic CR diffusion (blue). Different symbols indicate simulations of differently sized galaxy halos. In each simulation, we sample the SFR in logarithmic steps of e. Note that our simulations fall on the best-fit observational FIR–gamma-ray correlation (orange) and start to deviate from the calorimetric relation (dashed green) for small SFRs.