Numerical results of N-body simulation for the case with the effect of aggregate formation ( , ε _n = 0.5, τ = 10 ⁻²). (a) Normalized accretion rates as a function of the normalized time. The horizontal dotted line represents the results based on the three-body calculations, while the circles represent the results of N-body simulation. Open circles represent negative values of the accretion rate. (b) Number of particles contained in the aggregate formed on top of the moonlet, as a function of the normalized time.