Synthetic spectrum of H₂O and OH emission depending on the luminosity of the star, the accretion luminosity, the contribution of Lyα photons, and the gas-to-dust mass ratio. We recall that the fiducial model is a disk with a gas-to-dust mass ratio of d_gd = 10⁵ orbiting a T Tauri star with a stellar luminosity of L_* = 1 L_⊙, an accretion luminosity of L_acc = 0.12 L_⊙, and no contribution of Lyα to the impinging FUV field. The scales in panels d) and e) are different, highlighting the strong impact of the putative Lyα photons and the gas-to-dust ratio.