Ratio of the S(2) over the S(7) transition of H₂ against the shock velocity for different UV field strengths. The log(n_H) ranges from 2 to 6 from top to bottom, while magnetic field strength is b = 0.1 for the left column and 1 for the right. For all panels ζ = 10⁻¹⁷ s⁻¹, and X(PAH) = 10⁻⁷ are used. The shaded blue region marks the observed range of S(2)/S(7) ratios for the sources in Ophiuchus, while the beige region marks the range for Class 0 sources from Francis et al. (2025). Note that line intensities from Kristensen et al. (2023) are not available for all combinations of model parameters covered in the figure.