Macho project limits on black hole dark matter in the 1-30 M range

C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod, A. C. Becker, D. P. Bennett, K. H. Cook, N. Dalal, A. J. Drake, K. C. Freeman, M. Geha, K. Griest, M. J. Lehner, S. L. Marshall, D. Minniti, C. A. Nelson, B. A. Peterson, P. Popowski, M. R. Pratt, P. J. QuinnC. W. Stubbs, W. Sutherland, A. B. Tomaney, T. Vandehei, D. L. Welch

Research output: Contribution to journalArticlepeer-review


We report on a search for long-duration microlensing events toward the Large Magellanic Cloud. We find none and therefore put limits on the contribution of high-mass objects to the Galactic dark matter. At a 95% confidence level, we exclude objects in the mass range of 0.3-30.0 M from contributing more than 4 × 1011 M to the Galactic halo. Combined with earlier results, this means that objects with masses under 30 M cannot make up the entire dark matter halo if the halo is of typical size. For a typical dark halo, objects with masses under 10 M contribute less than 40% of the dark matter.

Original languageEnglish (US)
Pages (from-to)L169-L172
JournalAstrophysical Journal
Issue number2 PART 2
StatePublished - Apr 1 2001


  • Black hole physics
  • Dark matter
  • Galaxy: halo
  • Galaxy: structure
  • Gravitational lensing

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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