Simulations of spiral galaxies with an active potential: molecular cloud formation and gas dynamics

C. L. Dobbs, I. A. Bonnell

Research output: Contribution to journalArticlepeer-review

61 Citations (Scopus)

Abstract

We describe simulations of the response of a gaseous disc to an active spiral potential. The potential is derived from an N-body calculation and leads to a multi-armed time-evolving pattern. The gas forms long spiral arms typical of grand-design galaxies, although the spiral pattern is asymmetric. The primary difference from a grand-design spiral galaxy, which has a consistent two-/four-armed pattern, is that instead of passing through the spiral arms, gas generally falls into a developing potential minimum and is released only when the local minimum dissolves. In this case, the densest gas is coincident with the spiral potential, rather than offset as in the grand-design spirals. We would therefore expect no offset between the spiral shock and star formation, and no obvious corotation radius. Spurs which occur in grand-design spirals when large clumps are sheared off leaving the spiral arms, are rare in the active, time-evolving spiral reported here. Instead, large branches are formed from spiral arms when the underlying spiral potential is dissolving due to the N-body dynamics. We find that the molecular cloud mass spectrum for the active potential is similar to that for clouds in grand-design calculations, depending primarily on the ambient pressure rather than the nature of the potential. The largest molecular clouds occur when spiral arms collide, rather than by agglomeration within a spiral arm.

Original languageEnglish
Pages (from-to)1893-1902
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume385
DOIs
Publication statusPublished - 21 Apr 2008

Keywords

  • hydrodynamics
  • ISM : clouds
  • ISM : molecules
  • stars : formation
  • galaxies : spiral
  • galaxies : structure
  • GRAND DESIGN SPIRALS
  • STAR-FORMATION
  • INTERSTELLAR CLOUDS
  • VELOCITY DISPERSION
  • SHOCKS
  • MASS
  • TURBULENCE
  • FLOCCULANT
  • MODELS
  • SPURS

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