Outcome of varying the orbital parameters on the merger mock simulations. Top panel: Time evolution of the hydrostatic mass bias, evaluated at R_vir, for different values of the mass ratio q. The impact parameter is fixed to p = 0, and the horizontal axis represents the time elapsed since the beginning of the test. The vertical dashed line represents the moment at which the infalling halo centre enters the virial volume of the host. Bottom panel: Same evolution as the top figure but with a fixed mass ratio of q = 0.3 and a varying impact parameter.