SMALL-SCALE STRUCTURE OF DARK-MATTER AND MICROLENSING

It has been revealed, using microlensing, that a considerable part, po ssibly more than half of the dark matter in the halo of our Galaxy con sists of objects with mass spectrum ranging from 0.05 to 0.8 of the Su n mass. What is the nature of these objects? There exist two hypothese s. According to one of them these are the Jupiter type planets or smal l stars (brown and white dwarfs) that consist of usual baryonic matter . According to the other hypothesis, these are noncompact objects, i.e ., small-scale formations occurring in non-baryonic dark matter. Propo sed here is a theory that describes the possibility of the existence o f noncompact objects in the halo of our Galaxy, their structure and fo rmation in non-baryonic matter. The theory of microlensing on compact and noncompact objects is considered in detail. The results of microle nsing observations are described and compared with the theory. Possibl e astrophysical manifestations of the presence of small-scale structur e are pointed out. The field is being extensively studied and is of fu ndamental interest for cosmology and astrophysics.