Searching for Dark Matter Annihilation in the Smith High-Velocity Cloud
Recent observations suggest that some high-velocity clouds may be confined by massive dark matter halos. In particular, the proximity and proposed dark matter content of the Smith Cloud make it a tempting target for the indirect detection of dark matter annihilation. We argue that the Smith Cloud may be a better target than some Milky Way dwarf spheroidal satellite galaxies and use γ-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant γ-ray excess is found coincident with the Smith Cloud, and we set strong limits on the dark matter annihilation cross section assuming a spatially extended dark matter profile consistent with dynamical modeling of the Smith Cloud. Notably, these limits exclude the canonical thermal relic cross section (∼ 3 × 10−26 cm3 s−1) for dark matter masses ≲ 30 GeV annihilating via the ��¯ or τ+τ− channels for certain assumptions of the dark matter density profile; however, uncertainties in the dark matter content of the Smith Cloud may significantly weaken these constraints.
The Astrophysical Journal
Digital Object Identifier (DOI)
Drlica-Wagner, A., Gomez-Vargas, G. A., Hewitt, J. W., Linden, T., & TIBALDO, L. (2014). SEARCHING FOR DARK MATTER ANNIHILATION IN THE SMITH HIGH-VELOCITY CLOUD. The Astrophysical Journal, 790(1), 1–7. https://doi.org/10.1088/0004-637X/790/1/24