Left: the ṅ_ion fraction of galaxies at 6 ≤ z ≤ 9 as function of the M₁₅₀₀. Triangles represent the ṅ_ion obtained from the predicted f_esc as a function of M₁₅₀₀ in each bin. Bars represent the extrapolated value, i.e. the ṅ_ion fraction derived assuming that for M₁₅₀₀ > −18 a f_esc value constant and equal to 0.10, and for M₁₅₀₀ < −22 a f_esc value constant and equal to 0.05. Right: in yellow we show the ṅ_ion fraction of galaxies at 6 ≤ z ≤ 9 as function of M₁₅₀₀ changing, respectively, from the top left to the bottom right, the f_esc values at the faint-end (0.05 and 0.15) and the α parameter of the ρ_UV (−1.94 and −2.27). The original result is also shown with the same symbols as in the figure from the left.