Gamma ray signals of the annihilation of Higgs-portal singlet dark
  matter
  This article is an exploration of gamma ray signals of annihilating
Higgs-portal singlet scalar and vector dark matter. Gamma ray signals are
considered in the context of contributions from annihilations of singlets in
the galactic halo to the Isotropic Gamma Ray Background (IGRB), in the context
of the Galactic center excess, and in the context of observations of dwarf
spheroidal galaxies. We find that Higgs-portal singlets of both species with a
mass of $~$65 GeV can explain the Galactic center excess with reasonable
accuracy, but that this mass range is in tension with current direct detection
bounds. We also find that singlets in the mass range of 250-1000 GeV are
consistent with both the Fermi-LAT IGRB observations and direct detection
bounds. Additionally, bounds from gamma ray observations of the dwarf
spheroidal galaxy Segue I are translated into bounds on the Higgs-portal
couplings.
