Galactic positrons from Z super 0 decay

The positron excess below 10 GeV in the Galactic cosmic rays is shown to closely resemble the expected spectrum from sub-relativistic Z super 0 decay. The possibility is critically examined that the Galactic dark matter is composed of neutralinos that are just above the half the Z super 0 mass, and that the excess positrons derive from 'decay' of virtual Z super 0 bosons produced when the neutralinos annihilate. While this mechanism provides a very good fit for energies below 10 GeV, at higher energy it seems to disagree with the data given conventional assumptions about propagation.