Hunting for Heavy Winos in the Galactic Center
Résumé
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° and 4° 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.
Mots clés
Astrophysics and astroparticle physics
photon: energy spectrum
Cherenkov counter: atmosphere
energy resolution: effect
dark matter: interaction
dark matter: density
Wino: heavy
dark matter: annihilation
galaxy
WIMP
thermal
effective field theory
finite energy
gamma ray: flux
cosmic radiation: flux
soft collinear effective theory
pi: decay
gamma ray: VHE
electron: background
HESS
electroweak interaction
numerical calculations: Monte Carlo
showers: hadronic
sensitivity
imaging
spectral
tension
statistical