Histogram of the ${\chi }_{\text{red}}^2$ distribution of the 3000 realizations of the simulated cloud with initial conditions obtained from sampling the posterior distribution of the orbital fit of X7. The solid blue line and orange area represent the results of the fiducial case and the one considering the drag force of the ambient medium, respectively. The minimum value is ${\chi }_{\text{red}}^2=3.75$ in both cases.