Power spectrum tomography of dark matter annihilation with local galaxy
  distribution
  Cross-correlating the gamma-ray background with local galaxy catalogs
potentially gives stringent constraints on dark matter annihilation. We provide
updated theoretical estimates of sensitivities to the annihilation cross
section from gamma-ray data with Fermi telescope and 2MASS galaxy catalogs, by
elaborating the galaxy power spectrum and astrophysical backgrounds, and
adopting the Markov-Chain Monte Carlo simulations. In particular, we show that
taking tomographic approach by dividing the galaxy catalogs into more than one
redshift slice will improve the sensitivity by a factor of a few to several. If
dark matter halos contain lots of bright substructures, yielding a large
annihilation boost (e.g., a factor of $\sim$100 for galaxy-size halos), then
one may be able to probe the canonical annihilation cross section for thermal
production mechanism up to masses of $\sim$700 GeV. Even with modest
substructure boost (e.g., a factor of $\sim$10 for galaxy-size halos), on the
other hand, the sensitivities could still reach a factor of three larger than
the canonical cross section for dark matter masses of tens to a few hundreds of
GeV.
