Possible evidence for axino dark matter in the galactic bulge

Abstract

Recently, the SPI spectrometer on the INTEGRAL satellite observed strong 511 keV line emission from the galactic bulge. Although the angular distribution (spherically symmetric with width of $\ensuremath{\sim}9\ifmmode^\circ\else\textdegree\fi{}$) of this emission is difficult to account for with traditional astrophysical scenarios, light dark matter particles could account for the observation. In this paper, we consider the possibility that decaying axinos in an Repartee violating model of supersymmetry may be the source of this emission. We find that $\ensuremath{\sim}1\ensuremath{-}300\text{ }\text{ }\mathrm{M}\mathrm{e}\mathrm{V}$ axinos with R-parity violating couplings can naturally produce the observed emission.