SUSY in the sky or a keV signature of sub-GeV gravitino dark matter
  We point out that recently discovered 3.5 keV line in X-ray spectra from various galaxy clusters and the Andromeda galaxy can be naturally explained by physics of a sector responsible for spontaneous supersymmetry breaking in models with R-parity. In this scenario the source of this line could be decay of sgoldstino - scalar superpartner of massive gravitino. At the same time the dominant dark matter component is stable gravitino whose mass is predicted to be about 0.25 GeV. 
S.V. Demidov, D.S. Gorbunov
hep-ph astro-ph.HE