Microlensing Rates from Self-consistent Galactic Models

We study different models of dark matter distribution for the halo of ourgalaxy. In particular, we consider Eddington and King-Michie models, which[C[C, which include anisotropy in the velocity space, and compute in aself-consistent way the amount of dark matter present in the halo. Assumingthat the dark matter is in form of MACHOs, we find for each model the expectednumber of microlensing events and their average time duration for an experimentmonitoring stars in the LMC. The main effect of including anisotropy is toreduce the microlensing rate by about 30% and to increase, but only slightly,the mean event duration as compared to the standard halo model. Considerationof different luminous models for the visible part of the galaxy also inducevariations in the microlensing results by roughly the same amount as mentionedabove. The main uncertainty, in order to be able to discriminate betweendifferent dark matter distributions and to estimate the fraction of it in formof MACHOs is due to the poor knowledge of the rotation velocity at largegalactocentric distances.Comment: latex file, 2 figures to be requested at ingrosso@lecce.infn.i