Are there MACHOs in the Milky Way halo?

Abstract

Microlensing searches aim to detect compact halo dark matter via its gravitational lensing effect on stars within the Large Magellanic Cloud. The most recent results have led to the claim that roughly one fifth of the galactic halo dark matter may be in the form of compact, solar-mass objects. We analyze this hypothesis by considering the goodness-of-fit of the best-fit halo dark matter solutions to the observational data. We show that the distribution of the durations of the observed microlensing events is narrower than that expected to result from a standard halo lens population at 90 to 95% confidence. Only when the fraction of expected background (non-halo) events is significantly increased does the discrepancy between the observed and theoretical event duration distributions disappear. This indicates that it is possible that most of the lenses responsible for the observed microlensing events are not located within the Milky Way halo.

5 pages, 2 figures, minor changes to discussion and additional references, version to appear in Astronomy and Astrophysics

References in corpus (4)

• MACHO Project Limits on Black Hole Dark Matter in the 1-30 Solar Mass Range
• Direct Detection of Galactic Halo Dark Matter
• MACHO 96-LMC-2: Lensing of a Binary Source in the LMC and Constraints on the Lensing Object
• The Galactic Halo from Microlensing

Cited by in corpus (10)

• TOPICAL REVIEW: General relativistic boson stars
• Computations of primordial black hole formation
• Clustering of primordial black holes: Basic results
• The Origin of the Microlensing Events Observed Towards the LMC and the Stellar Counterpart of the Magellanic Stream
• Large Magellanic Cloud Microlensing Optical Depth with Imperfect Event Selection
• Monte Carlo simulations of the halo white dwarf population
• Microlensing towards LMC: a study of the LMC halo contribution
• Possibility of Magnetic Mass Detection by the Next Generation of Microlensing Experiments
• Microlensing by the Halo MACHOs with Spatially Varying Mass Function
• Statistical Interpretation of LMC Microlensing Candidates