FEMTOLENSING AND PICOLENSING BY AXION MINICLUSTERS

Nonlinear effects in the evolution of the axion field in the early uni verse may lead to the formation of gravitationally bound clumps of axi ons, known as ''miniclusters.'' Minicluster masses and radii should be in the range M(mc) similar to 10(-12) M. and R(mc) similar to 10(10) cm, and in plausible early-universe scenarios a significant fraction o f the mass density of the universe may be in the form of axion miniclu sters. If such axion miniclusters exist, they would have the physical properties required to be detected by ''femtolensing.''