The significance of ultracompact minihalos as the astrophysical sources

The ultracompact minihalos would be formed during the earlier epoch of cosmology. The dark matter annihilation within them is very strong due to the high density. The electron and positron with high energy from the dark matter annihilation can inverse Compton scatter (ICS) the background photons, such as CMB photons, into the higher energy. On the other hand, the synchrotron radiation can also be produced when they meet the magnetic field. In this paper, we study the signals from the UCMHs due to the dark matter annihilation into the radio, x-ray and {\gamma}-ray bands. We found that for the radio emission the UCMHs can provide one kinds of sources of the radio excess observed by ARCADE 2. But for these dark matter models, the x-ray signals due to the ICS effect and the {\gamma}-ray signals mainly due to the prompt emission from dark matter would excess the present observations, such as Fermi, COMPTEL and CHANDRA.