  A generic feature of weakly interacting massive particle (WIMP) dark matter
models is the emission of photons over a broad energy band resulting from the
stable yields of dark matter pair annihilation. Inverse Compton scattering off
cosmic microwave background photons of energetic electrons and positrons
produced in dark matter annihilation is expected to produce significant diffuse
X-ray emission. Dwarf galaxies are ideal targets for this type of dark matter
search technique, being nearby, dark matter dominated systems free of any
astrophysical diffuse X-ray background. In this paper, we present the first
systematic study of X-ray observations of local dwarf galaxies aimed at the
search for WIMP dark matter. We outline the optimal energy and angular ranges
for current telescopes, and analyze the systematic uncertainties connected to
electron/positron diffusion. We do not observe any significant X-ray excess,
and translate this null result into limits on the mass and pair annihilation
cross section for particle dark matter. Our results indicate that X-ray
observations of dwarf galaxies currently constrain dark matter models at the
same level or even more strongly than gamma-ray observations of the same
systems, although at the expenses of introducing additional assumptions and
related uncertainties in the modeling of diffusion and energy loss processes.
The limits we find constrain portions of the supersymmetric parameter space,
particularly if the effect of dark matter substructures is included. Finally,
we comment on the role of future X-ray satellites (e.g. Constellation-X, XEUS)
and on their complementarity with GLAST and other gamma-ray telescopes in the
quest for particle dark matter.
