Overview of the different regimes for the static (σ_cl = v_max = 0) setup. The color coding shows our (interpolated) numerical results in terms of the flux at line center divided by the peak flux of the spectrum, i.e., a value of ~ 0 [~ 1] quantifies a double- [single-]peaked spectrum. Specifically this quantity is 1/2 at the solid line. The dashed line indicates the f_{c, crit} (Eq. (10)), and the dotted line is the boundary to the low-density regime (τ_0,total = 1).