Deviation from the local Σ_[C II] − Σ_SFR relation Δ vs. the C III] over [C II] surface brightness ratio, color-coded by the SFR per unit area Σ_SFR. Galaxies detected both in [C II] and C III] emission are annotated. We plot a grid of model predictions with fixed metallicity and gas density, with the burstiness parameter varying in a range of 0 ≤ log(κ_s) ≤ 2.4 i.e., κ_s = 1, 5, 10, 30, 50, 100, 250 (dotted lines), and log(Σ_SFR[M_⊙ yr⁻¹]) in −0.5 ≤ log(Σ_SFR[M_⊙ yr⁻¹]) ≤ 2.5 (solid lines). The top panel shows an example of a model prediction for high-z galaxies with ISM properties similar to HZ10, with solar metallicity Z = Z_⊙ and gas density close to critical density of log(n[cm⁻³]) = 3.3. Bottom panel shows predictions for typical high-z galaxies with subsolar metallicity Z = 0.5 Z_⊙ and log(n[cm⁻³]) = 2.5.