We argue that we may be able to sort out dark matter models in which
electrons are generated through the annihilation and/or decay of dark matter,
by using a fact that the initial energy spectrum is reflected in the cosmic-ray
electron flux observed at the Earth even after propagation through the galactic
magnetic field. To illustrate our idea we focus on three representative initial
spectra: (i)monochromatic (ii)flat and (iii)double-peak ones. We find that
those three cases result in significantly different energy spectra, which may
be probed by the Fermi satellite in operation or an up-coming cosmic-ray
detector such as CALET.Comment: 19 pages, 8 figure