  Annihilation of cosmologically distributed dark matter is predicted to
produce a potentially observable flux of high energy photons. Neglecting the
contribution from local structure, this signal is predicted to be virtually
uniform on the sky and, in order to be identified, must compete with various
extragalactic backgrounds. We focus here on unresolved blazars and discuss
several techniques for separating the dark matter signal from this background.
First, the spectral shapes of the signal and background are expected to differ,
a feature which can be exploited with the Fisher Matrix formalism. Second, in
any given angular pixel, the number of photons from blazars is drawn from a
distribution which is far from Poisson. A knowledge of this distribution
enhances one's ability to extract the dark matter signal, while ignorance of it
can lead to the introduction of a large systematic error.
