Halo White Dwarfs
Halo White Dwarf Survey
  • 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 Papers I, II & 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 first file gives photometric and astrometric data for all the objects plotted in Figure 1 of our paper. The second file 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.
  • "White Dwarfs: 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 .