The Formation and Evolution of First Dark Matter Microhalos

The smallest dark matter microhalos are the first structures formed in the Universe. We present the results of high-resolution simulations of the formation and evolution of first dark matter microhalos. We found that the central density cusps of microhalos are the form rho proportional to r(-1.5), steeper than the cusps of larger dark halos. Their central regions are not disrupted by tidal forces from the parent galaxies and stars. The annihilation signals from nearest microhalos could be observed as gamma-ray point-sources (radius less than 1'), with unusually large proper motions of similar to 0.2 degree per year.