Dark matter line search using a joint analysis of dwarf galaxies with the Fermi Gamma-ray Space Telescope

We perform a joint analysis of dwarf galaxy data from the Fermi Gamma-ray Space Telescope in search of dark matter annihilation into a gamma-ray line. We employ a novel statistical method that takes into account the spatial and spectral information of individual photon events from a sample of seven dwarf galaxies. Dwarf galaxies show no evidence of a gamma-ray line between 10 GeV and 1 TeV. The subsequent upper limit on the annihilation cross section to a two-photon final state is 3.9(-3.7)(+7.1) X 10(-26) cm(3) s(-1) at 130 GeV, where the errors reflect the systematic uncertainty in the distribution of dark matter within the dwarf galaxies.