Age – velocity dispersion relations for the isolated white dwarfs (left panels), the white dwarfs in common proper motion pairs (middle panels), and the combined samples (right panels). Each row shows the results obtained by considering two white dwarf progenitor age estimates, which are based on the progenitor masses that we derived through the Catalán et al. (2008) and Cummings et al. (2018) IFMRs, or the average of the two. The three velocity components use different symbols and colors, as is shown in the legend of the top panels. The shaded regions in the bottom panels represent the 16–84% ranges of the Cheng et al. (2019) formulation for the age – velocity dispersion of white dwarfs in the Galactic thin and thick disk. The dashed curves represent the extrapolated thin-disk contribution.