Hunting for Heavy Winos in the Galactic Center
  Observing gamma rays using ground-based atmospheric Cherenkov telescopes
provides one of the only probes of heavy weakly interacting dark matter. A
canonical target is the thermal wino, for which the strongest limits come from
searches for photon lines from annihilations in the Galactic Center.
Irreducible finite energy resolution effects motivate refining the prediction
for a wino signal beyond the photon line approximation; recently, modern
effective field theory techniques have been utilized to obtain a precise
calculation of the full photon energy spectrum from wino annihilation. In this
paper, we investigate the implications for a realistic mock H.E.S.S.-like line
search. We emphasize the impact of including the non-trivial spectral shape,
and we carefully treat the region of interest, presenting results for choices
between $1^{\circ}$ and $4^{\circ}$ from the Galactic Center. Projected limits
for wino masses from $1$-$70$ TeV are interpreted as a constraint on the wino
annihilation rate, or alternatively as the minimum core size required such that
the wino is not excluded. If there is a thermal wino, H.E.S.S. will be able to
probe cores of several kpc, which would begin to cause tension between this
dark matter candidate and astrophysical observations/simulations.
