Searching for Dark Matter Annihilation in the Smith High-Velocity Cloud

Abstract

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 gamma-ray observations from the Fermi Large Area Telescope to search for a dark matter annihilation signal. No significant gamma-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 ($\sim 3\times 10^{-26}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$) for dark matter masses $\lesssim 30$ GeV annihilating via the $b\bar{b}$ or ${\tau }^{+}{\tau }^{-}$ 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.

7 pages, 5 figures. Published in ApJ

References in corpus (7)

• Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope
• Pre-launch estimates for GLAST sensitivity to Dark Matter annihilation signals
• Fitting the Gamma-Ray Spectrum from Dark Matter with DMFIT: GLAST and the Galactic Center Region
• Smith's Cloud: A High-velocity Cloud Colliding with the Milky Way
• Constraining Extended Gamma-ray Emission from Galaxy Clusters
• Ionized Gas in the Smith Cloud
• Relics of structure formation: extra-planar gas and high-velocity clouds around the Andromeda Galaxy

Cited by in corpus (9)

• Search for Gamma-ray Emission from Dark Matter Annihilation in the Large Magellanic Cloud with the Fermi Large Area Telescope
• Fermi-LAT Observations of High- and Intermediate-Velocity Clouds: Tracing Cosmic Rays in the Halo of the Milky Way
• The Mopra Southern Galactic Plane CO Survey - Data Release 3
• Search for $\gamma$-ray emission from dark matter particle interactions from Andromeda and Triangulum Galaxies with the Fermi Large Area Telescope
• Simplified Dark Matter Models Confront the Gamma Ray Excess
• Strong Optimized Conservative Fermi-LAT Constraints on Dark Matter Models from the Inclusive Photon Spectrum
• TeV Dark Matter Searches in the Extragalactic Gamma-Ray Sky
• Search for gamma-ray line features from Milky Way satellites with Fermi-LAT Pass 8 data
• Dark matter properties implied by gamma ray interstellar emission models