Constraints on ultracompact minihalos using neutrino signals from gravitino dark matter decay

Ultracompact dark matter minihalos(UCMHs) would be formed during the early universe if there were large density perturbations.If dark matter can decay into particles described by the standard model,such as neutrinos,these objects would become potential astrophysical sources of emission which could be detected by instruments such as IceCube.In this paper,we investigate neutrino signals from nearby UCMHs due to gravitino dark matter decay and compare these signals with the background neutrino flux which is mainly from the atmosphere to obtain constraints on the abundance of UCMHs.