Local stability curves for black hole masses for 10 M_⊙ (left panel), 10⁵ M_⊙ (middle panel), and 10⁷ M_⊙ (right panel). For each curve, we keep R = 10R_schw and α = 0.01. The color of the S-curve represents different coefficient values for model B: blue for b′ = 0 (base model), orange for b′ = 0.5, and brown for b′ = 0.9. For each plot, we keep the same X-axis and the same range (3 orders of magnitude) for the Y-axis.