(top) MCMC best-fit model for the red (left) and blue (right) velocity components of the expanding ellipsoid shown as contours overimposed on the observed velocity maps shown in Fig. 5, and (bottom) absolute differences between the MCMC best-fit model and the velocity maps in Fig. 5 with respect to each image pixel velocity dispersion. The center is located at position (0,0) as marked with a white cross.