Mass weighted gas profiles for the isolated halo types and the fly-by collision scenario, compared at 5 Myr after the formation of the first sink particle, i.e. when the sink particle is deeply embedded in the dense, shocked region (see the middle panel of Fig. 5). Left: Mass of gas at or above density thresholds as a function of the density threshold. Right: Cumulative mass as a function of radius from the sink particle.