X-ray line signal from 7 keV axino dark matter decay

摘要

Recently a weak X-ray emission around E γ ? 3.5 ? keV was detected in the Andromeda galaxy and various galaxy clusters including the Perseus galaxy cluster but its source has been unidentified. Axino, the superpartner of axion, with a mass 2 E γ is suggested as a possible origin of the line with R-parity violating decay into photon and neutrino. Moreover, most of parameter space is consistent with recent observation by the BICEP2 experiment.