Contour plot of the number of BBH mergers (solid blue lines and associated labels) in the two planes summarizing the effects of the main parameter dependence: initial half-mass radius versus initial stellar mass (by assuming a primordial binary fraction of 10%; left panel), and primordial binary fraction versus average initial density within r_h (by assuming an initial stellar mass of 3 × 10⁶ M_⊙; right panel). The dashed red lines and the corresponding red labels show the contour plot of the ratio between the number of dynamical to primordial BBH mergers.