[CII] /FIR ratio as a function of the FIR surface density (Σ_FIR) for HZ10-C (blue square), HZ10-W (orange square), and the bridge between them (green empty square). For comparison, the figure also includes nearby star-forming and starburst galaxies from the SHINING sample (grey filled stars; Herrera-Camus et al. 2018a), ∼100 pc scale regions in the central disk of M82 (green unfilled dots; Contursi et al. 2013; Herrera-Camus et al. 2018a), ∼400 pc scale regions from central regions of M83 (purple filled circles), lensed dusty star-forming galaxies at z ∼ 1.9 − 5.7 (DSFGs; red-solid diamonds; Spilker et al. 2016), and four kpc-size regions extracted across the disk of HZ04 (red unfilled triangles; Herrera-Camus et al. 2021). The solid grey line corresponds to the best quadratic fit to the SHINING data (as included in Herrera-Camus et al. 2018a).