Top: similar to Fig. 1, but Σ_gas was calculated over the 3 GHz radio sizes derived by M17a (the magenta ellipses in Fig. A.1). Each bin contains five sources. Bottom: similar to the top panel, but both Σ_gas and Σ_SFR were calculated over the 3 GHz radio sizes. Each MS (SB) bin contains four (five) sources, where the one additional source compared to the top panel is the 3 GHz detected SMG AzTEC/C8b. In both panels, the three sources unresolved at 3 GHz (lower limit to Σ_gas in the top panel, and to both Σ_gas and Σ_SFR in the bottom panel) were incorporated into the binned averages using a right-censored K-M survival analysis. The K98 relationship is shown for comparison. The plotting ranges of the two panels are different for legibility purposes.