Sketch of the conical domain chosen to represent the DZ when the field lines are not advected by the contraction. The displayed meridional cut of the normalised rotation rate is the same as in the first panel of Fig. 3. The conical domain, delimited by thick black lines on the meridional cut, is defined by r ∈ [r_iDZ;r₀] and θ ∈ [−θ₀;θ₀], with r_iDZ = 0.77r₀, θ₀ ≈ π/14, and −θ₀ ≈ −π/14 or equivalently, in terms of colatitude, θ ∈ [3π/7;4π/7].