Microlensing implications for halo dark matter

Abstract

The French collaboration EROS and the American-Australian collaboration MACHO have reported the observation of altogether $\sim$ 10 microlensing events by monitoring during several years the brightness of millions of stars in the Large Magellanic Cloud. In particular the MACHO team announced the discovery of 8 microlensing candidates by analysing their first 2 years of observations. This would imply that the halo dark matter fraction in form of MACHOs (Massive Astrophysical Compact Halo Objects) is of the order of 45-50%. The most accurate way to get information on the mass of the MACHOs is to use the method of mass moments. For the microlensing events detected so far by the MACHO collaboration in the Large Magellanic Cloud the average mass turns out to be 0.27$M_{\odot}$.