Dependence of a₁ and a₂ on both ζ and d. The size of the symbols depicts the value of the final mass of the BH. Top panel: a₂ as a function ζ for initial d_* = 2, d_* = 3 and d_* = 5. Bottom panel: a₁ as a function ζ for initial d_* = 2, d_* = 3 and d_* = 5, under the assumption that M₁ had no spin before the final SN explosion a₁(t = 0) = 0.