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Oscar Agertz. Profile photo.

Oscar Agertz

Assistant Professor / Associate senior university lecturer / Wallenberg Academy Fellow

Oscar Agertz. Profile photo.

The Smith Cloud and its dark matter halo : Survival of a galactic disc passage

Author

  • Matthew Nichols
  • Nestor Mirabal
  • Oscar Agertz
  • Felix J. Lockman
  • Joss Bland-Hawthorn

Summary, in English

Under conservative assumptions about the Galaxy, the derived velocity of the Smith Cloud indicates that it will have undergone at least one passage of the Galactic disc. Using hydrodynamicsimulations, we examine the present-day structure of the Smith Cloud and find that a dark matter supported cloud is able to reproduce the observed present-day neutral hydrogen mass, column density distribution and morphology. In this case, the dark matter halo becomes elongated owing to the tidal interaction with the Galactic disc. Clouds in models neglecting dark matter confinement are destroyed upon disc passage, unless the initial cloud mass is well in excess of what is observed today. We then determine integrated flux upper limits to the gamma-ray emission around such a hypothesized dark matter core in the Smith Cloud. No statistically significant core or extended gamma-ray emission are detected down to a 95 per cent confidence level upper limit of 1.4 × 10-10 ph cm-2 s-1 in the 1-300 GeV energy range. For the derived distance of 12.4 kpc, the Fermi upper limits set the first tentative constraints on the dark matter cross-sections annihilating into τ+τ- and bb for a high-velocity cloud.

Publishing year

2014-01-01

Language

English

Pages

2883-2891

Publication/Series

Monthly Notices of the Royal Astronomical Society

Volume

442

Issue

4

Document type

Journal article

Publisher

Oxford University Press

Keywords

  • Dark matter
  • Galaxy: halo
  • Gamma-rays: general
  • ISM: clouds
  • ISM: individual objects: Smith Cloud

Status

Published

ISBN/ISSN/Other

  • ISSN: 0035-8711