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We present a magnitude and proper motion limited catalogue of ~10,000 whitedwarf candidates, obtained from the SuperCOSMOS Sky Survey by means of reducedproper motion selection. This catalogue extends to magnitudes r~19.75 andproper motions as low as mu ~0.05"/yr, and covers nearly three quarters of thesky. Photometric parallaxes provide distance estimates accurate to ~50%. Thiscatalogue is used to measure the luminosity functions for disk and spheroidwhite dwarfs, using strict velocity cuts to isolate subsamples belonging toeach population. Disk luminosity functions measured in this manner are really aconglomerate of thin and thick disk objects, due to the significant velocityoverlap between these populations. We introduce a new statistical approach tothe stellar luminosity function for nearby objects that succesfully untanglesthe contributions from the different kinematic populations, without the needfor stringent velocity cuts. This improves the statistical power by allowingall stars to contribute to the luminosity function, even at tangentialvelocities where the populations are indistinguishable. This method isparticularly suited to white dwarfs, for which population discrimination bychemical tagging is not possible. We use this technique to obtain the firstmeasurement of the thick disk white dwarf luminosity function, while alsoimproving constraint on both the thin disk and spheroid luminosity functions.We find that the thin disk, thick disk and spheroid populations contribute tothe local white dwarf density in roughly 79%/16%/5% proportions.

White Dwarfs in the SuperCOSMOS Sky Survey: the Thin Disk, Thick Disk and Spheroid Luminosity Functions