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An excess in gamma-rays from the galactic center observed by the Fermi LargeArea Telescope has been proposed as a possible signal of dark matterannihilation. Recently, the Fermi collaboration showed that systematic errorsbroaden the range of spectral shapes for this excess. We demonstrate fits tothis range for (1) flavor-violating annihilations to top-charm pairs and (2)annihilations to on-shell bosonic mediators which decay to Standard Modelquarks in a boosted frame. Annihilation of 40 - 100 GeV DM to pairs of spin-1mediators provide a good fit to the Fermi-LAT spectrum with a normalizationconsistent with a thermal relic. Top-charm modes and annihilation to threepseudoscalar mediators can fit the spectral shape but typically requirenon-thermal annihilation cross sections.

On-Shell Mediators and Top-Charm Dark Matter Models for the Fermi-LAT Galactic Center Excess