Left plot: joint probability density of -v_circ. Right plot: joint space densities distribution, estimated by weighting the KDE kernels by the 1 /V_max weights. Grey lines denote the 1, 2, and 3 standard deviation contours. The black line shows the TFR discussed in the previous section. A 1σ contour of the Gaussian kernel used for density estimation is shown in the upper left corners. Grey shaded regions mark the regions where our sample is incomplete.