  If the present dark matter in the Universe annihilates into Standard Model
particles, it must contribute to the gamma ray fluxes detected on the Earth.
The magnitude of such contribution depends on the particular dark matter
candidate, but certain features of the produced spectra may be analyzed in a
rather model-independent fashion. In this communication we briefly revise the
complete photon spectra coming from WIMP annihilation into Standard Model
particle-antiparticle pairs obtained by extensive Monte Carlo simulations and
consequent fitting functions presented by Dombriz et al. in a wide range of
WIMP masses. In order to illustrate the usefulness of these fitting functions,
we mention how these results may be applied to the so-called brane-world
theories whose fluctuations, the branons, behave as WIMPs and therefore may
spontaneously annihilate in SM particles. The subsequent $\gamma$-rays signal
in the framework of dark matter indirect searches from Milky Way dSphs and
Galactic Center may provide first evidences for this scenario.
