Microlensing implications for halo dark matter

Abstract

The observations of microlensing events in the Large Magellanic Cloud suggest that a sizable fraction ($\sim$ 50%) of the galactic halo is in the form of MACHOs (Massive Astrophysical Compact Halo Objects) with an average mass $\sim 0.27M_{\odot }$, assuming a standard spherical halo model. We describe a scenario in which dark clusters of MACHOs and cold molecular clouds (mainly of $H_2$) naturally form in the halo at galactocentric distances larger than 10--20 kpc.

3 pages, to appear in Proceedings of the 8th Marcel Grosmann Meeting on relativistic Astrophysics, Jerusalem, 22-27 June 1997