Constraints on the ultracompact minihalos using neutrino signals from   the gravitino dark matter decay
  Ultracompact dark matter minihalos (UCMHs) would be formed during the earlier universe if there were large density perturbations. If the dark matter can decay into the standard model particles, such as neutrinos, these objects would become the potential astrophysical sources and could be detected by the related instruments, such as IceCube. In this paper, we investigate the neutrino signals from the nearby UCMHs due to the gravitino dark matter decay and compare these signals with the background neutrino flux which is mainly from the atmosphere to get the constraints on the abundance of UCMHs. 
Yun-Long Zheng, Yu-Peng Yang, Ming-Zhe Li and Hong-Shi Zong
astro-ph.CO