Known Unknowns of Dark Matter Annihilation over Cosmic Time
  Dark matter self-annihilation holds promise as one of the most robust
mechanisms for the identification of the particle responsible for the
Universe's missing mass. In this work, I examine the evolution of the dark
matter annihilation power produced by smooth and collapsed structures over
cosmic time, taking into account uncertainties in the structure of dark matter
halos. As we search for observational signatures of annihilation, an
understanding of this time evolution will help us to best direct our
observational efforts, either with local measurements or investigation of the
effects of annihilation on the intergalactic medium at high redshift. As I show
in this work, there are several key sources of uncertainty in our ability to
estimate the dark matter annihilation from collapsed structures, including: the
density profile of dark matter halos; the small-scale cut-off in the dark
matter halo mass function; the redshift-dependent mass-concentration relation
for small halos; and the particle-velocity dependence of the dark matter
annihilation process. Varying assumptions about these quantities can result in
annihilation power predictions that differ by several orders of magnitude.
These uncertainties must be resolved, through a combination of observation and
modeling, before robust estimations of the cosmological annihilation signal can
be made.
