Search for High Proper Motion White Dwarfs

Recent results of microlensing surveys, show that 10-20 % of the dark halo mass of the Milky Way consists of compact objects. The masses of these compact objects range from 0.1 to 1 solar mass. New theoretical cooling models for white dwarfs, and the detection of faint blue high proper motion objects, imply that ancient white dwarfs might make up part of this population. In this pilot project, using data from the C and D patches of the ESO Imaging Survey and data obtained at CTIO, we attempted to find such halo white dwarfs in the solar neighbourhood. With a time baseline of approximately one year between data sets and a limiting I-band magnitude of 23, we can find these high proper motion objects up to distances of 85 parsecs. In the 2.5 deg 2 studied so far we have found three high proper motion candidates. 1 Introduction: dark matter and white dwarfs It is generally accepted that the Milky Way and most external galaxies contain more mass than observed directly. What makes up this so-called ‘dark mass ’ is, however, not so clear. This mass is often assumed to be distributed in an isothermal halo, which means that dark matter would also be present in the solar neighbourhood. Recent results from galactic microlensing