It has recently been pointed out that the annihilations of a class of possible dark-matter halo constituents (including photinos, Higgs fermions, and heavy neutrinos or scalar neutrinos) within the halo of our galaxy produce a series of narrow gamma-ray lines. If these lines are detected, then the directional dependence of the intensity of the lines provides a very powerful probe of the halo mass distribution, and the local density, core radius, and ellipticity of the halo could be readily determined. We also briefly comment on the possibility of detecting annihilations of weakly interacting massive particles which may be in the galactic spheroid.

• Received 7 April 1986

DOI:https://doi.org/10.1103/PhysRevD.34.1921