511 keV Line Emission from Nearby Spherical Dwarf Galaxies
  The observed galactic 511 keV line has been interpreted in a number of papers as a possible signal of dark matter annihilation within the galactic bulge. If this is the case then we should expect a similar spectral feature associated with nearby dwarf galaxies which are dark matter dominated. It has recently been argued [1] that the absence of such a signal excludes a dark matter explanation as the major source for the galactic 511 keV line. In the model presented here dark matter in the form of heavy quark nuggets produces the galactic 511 keV emission line through interactions with the visible matter. It is argued, however, that this type of interaction is not subject to the strong dark matter annihilation constraints presented in [1]. 
Kyle Lawson and Ariel Zhitnitsky
astro-ph.CO hep-ph