Comparison of structure parameter ζ estimated from observational data (black crosses) and calculated numerically. Virial mass is shown along the x-axes. From left to right, the outer temperature values are 10³, 3 × 10³ (upper panels), 5 × 10³, and 10⁴ K (lower panels). The three curves in every case correspond to different absolute mass accretion rates (solid blue, dashed red, and dotted green curves correspond to 1, 10, and 100 M_⊙ yr^-1, respectively). The horizontal dotted line corresponds to the standard disc limit ζ = 4/3. Everywhere the inflow half-opening angle is θ₀ = 45°.