Results of the Bayesian retrieval run on our GJ 1214 b high-resolution data. The free parameters of the retrieval were the planet’s temperature, T_iso, used to calculate an isothermal T-p profile, the opacity deck top pressure, log₁₀(P_c), the C/O ratio and metallicity [M/H] of the atmosphere, the system parameters K_p and v₀, and a scaling factor for the data uncertainties, β. Upper right: Posterior distributions for the metallicity [M/H] and opacity deck pressure, P_c, plotted in red as contours at the 0.5, 1.0, 1.5, and 2.0 σ level on top of the grid of expected S/N for different [M/H] and P_c from injection-recovery tests, for which S/N=3 and 4 contours are indicated as white lines.