White dwarf kinematics versus mass

We investigated the relationship between the kinematics and mass of young (<3 X 108 yr) white dwarfs using proper motions. Our sample is taken from the colour-selected catalogues of the Sloan Digital Sky Survey and the PalomarGreen Survey, both of which have spectroscopic temperature and gravity determinations. We find that the dispersion decreases with increasing white dwarf mass. This can be explained as a result of less scattering by objects in the Galactic disc during the shorter lifetime of their more massive progenitors. A direct result of this is that white dwarfs with high mass have a reduced scale height, and hence their local density is enhanced over their less massive counterparts. In addition, we have investigated whether the kinematics of the highest mass white dwarfs (>0.95?M?) are consistent with the expected relative contributions of single star evolution and mergers. We find that the kinematics are consistent with the majority of high-mass white dwarfs being formed through single star evolution.