EROS and MACHO combined limits on planetary-mass dark matter in the Galactic halo

C. Alcock, R. A. Allsman, D. Alves, R. Ansari, É Aubourg, T. S. Axelrod, P. Bareyre, J. P.H. Beaulieu, A. C. Becker, D. P. Bennett, S. Brehin, F. Cavalier, S. Char, K. H. Cook, R. Ferlet, J. Fernandez, K. C. Freeman, K. Griest, P. H. Grison, M. GrosC. Gry, J. Guibert, M. Lachièze-Rey, B. Laurent, M. J. Lehner, É Lesquoy, C. Magneville, S. L. Marshall, É Maurice, A. Milsztajn, D. Minniti, M. Moniez, O. Moreau, L. Moscoso, N. Palanque-Delabrouille, B. A. Peterson, M. R. Pratt, L. Prévôt, F. Queinnec, P. J. Quinn, C. Renault, J. Rich, M. Spiro, C. W. Stubbs, W. Sutherland, A. Tomaney, T. Vandehei, A. Vidal-Madjar, L. Vigroux, S. Zylberajch

Research output: Contribution to journalArticlepeer-review

123 Citations (Scopus)


The EROS and MACHO collaborations have each published upper limits on the amount of planetary-mass dark matter in the Galactic halo obtained from gravitational microlensing searches. In this Letter, the two limits are combined to give a much stronger constraint on the abundance of low-mass MACHOs. Specifically, objects with masses 10-7 M ≲ m ≲ 10-3 M make up less than 25% of the halo dark matter for most models considered, and less than 10% of a standard spherical halo is made of MACHOs in the 3.5 × 10-7 M < m < × 10-5 M mass range.

Original languageEnglish
Pages (from-to)L9-L12
JournalAstrophysical Journal
Issue number1 PART II
Publication statusPublished - 1998


  • Dark matter
  • Gravitational lensing
  • Stars: Low-mass, brown dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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