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On the reported death of the MACHO era

Research output: Contribution to journalJournal articlepeer-review

  • D. P. Quinn
  • M. I. Wilkinson
  • Michael J. Irwin
  • J. Marshall
  • Andreas Koch
  • V. Belokurov
<mark>Journal publication date</mark>29/04/2009
<mark>Journal</mark>Monthly Notices of the Royal Astronomical Society: Letters
Issue number1
Number of pages5
Pages (from-to)L11-L15
Publication StatusPublished
<mark>Original language</mark>English


We present radial velocity measurements of four wide halo binary candidates from the sample in Chaname & Gould (CG04) which, to date, is the only sample containing a large number of such candidates. The four candidates that we have observed have projected separations >0.1 pc, and include the two widest binaries from the sample, with separations of 0.45 and 1.1 pc. We confirm that three of the four CG04 candidates are genuine, including the one with the largest separation. The fourth candidate, however, is spurious at the 5σ level. In the light of these measurements, we re-examine the implications for MAssive Compact Halo Object (MACHO) models of the Galactic halo. Our analysis casts doubt on what MACHO constraints can be drawn from the existing sample of wide halo binaries.