Speaker
Description
Adding an electroweak triplet fermion, or wino, to the Standard Model gives one of the simplest particle explanations of dark matter. In addition to this bottom-up, economical motivation, such a state automatically arises in supersymmetric extensions of particle physics. For masses near 2.8 TeV, its relic density from thermal freezeout would provide a complete resolution of the dark matter puzzle. Since the wino participates in Standard Model gauge interactions, its annihilation produces energetic, nearly monochromatic gamma-ray photons. It is thus a prime target for indirect detection. We report here limits on the wino annihilation rate for masses from 800 GeV to 200 TeV using 638 hours of observation time on 17 dwarf spheroidal galaxies (dSphs) by the VERITAS imaging atmospheric Cherenkov telescope array. We utilize state-of-the-art theoretical calculations for the annihilation rate to photons and a conservative set of J-factors. While the existence of wino dark matter remains consistent with observation throughout much of the range we tested, this work shows that further study of dSphs offer a means to rule on this compelling model independent of Galactic Center observations.
