Microlensing Implications for Halo Dark Matter

Abstract

The most accurate way to get information on the mass of the MACHOs (Massive Astrophysical Compact Halo Objects) is to use the method of mass moments. For the microlensing events detected so far by the EROS and the MACHO collaborations in the Large Magellanic Cloud the average mass turns out to be 0.08$M_{\odot}$. Assuming a spherical standard halo model we find that MACHOs contribute about 20\% to the halo dark matter. The eleven events recorded by OGLE, mainly during its first two years of operation, in the galactic bulge lead to an average mass of 0.29$M_{\odot}$, whereas forty events detected by MACHO during its first year give 0.16$M_{\odot}$, thus suggesting that the lens objects are faint disk stars.