General questions regarding dark matter and white dwarfs
Direct Detection of Galactic Halo Dark Matter
Ben R. Oppenheimer, Nigel C. Hambly, Andrew P. Digby,
Simon T. Hodgkin and Didier Saumon
Science, Vol. 292, pp. 698-702 (27 April 2001)
This survey for white dwarfs used the
SuperCOSMOS Sky Survey.
A full description of the general survey properties can be found in
III which provide
an introduction, description, and technical details concerning plate
measurement, photometry and astrometry.
Two tables giving more information than appeared in the original Science
paper are available. The
gives photometric and astrometric data for all the objects plotted in
Figure 1 of our paper. The
gives further spectroscopic classification information for the subset
of objects selected (155 stars) via colour and/or reduced proper motion (ie.
the area of colour/RPM parameter space relevant to WDs). This
second list has all spurious and duplicated objects flagged via
PGPLOT symbol types indicating the spectroscopic nature of of each target.
Columns are otherwise the same as for the first file. Note that the first
file still has these spurious and duplicate objects included - 15 of the
objects listed in the first file (mainly at high RPM) could not be found at
the telescope and are probably not real (to see which ones, look in the
second file). Duplicate objects have not been expunged so that it is possible
to check our error estimates on the photometry and astrometry where
independent measurements exist for the same objects.
Discussion of an alternative interpretation of these results
Response to Technical Comments on the Oppenheimer et al. (2001) paper. This PDF file includes the technical comments themselves as well as our response all of which were refereed.
Contributors and Tracers of the Dark Matter Halo," by
L. V. E. Koopmans and R. D. Blandford, presents a maximum likelihood
analysis of the survey. Their results suggest that we may have
underestimated the space density of halo white dwarfs. Koopmans and
Blandford also suggest the intriguing possibility that the over
abundance of white dwarfs may be explained by ejection of white dwarfs
from the disk into the halo.
Presentation at "White Dwarfs as Dark
Matter" Conference, Vancouver, BC, August 21, 2001" (powerpoint file or web format IE only). See also The
conference proceedings website .