A search for kinematic evidence of radial gas flows in spiral galaxies

Tony Wong, Leo Blitz, Albert Bosma

Research output: Contribution to journalArticlepeer-review


CO and H I velocity fields of seven nearby spiral galaxies, derived from radio-interferometric observations, are decomposed into Fourier components whose radial variation is used to search for evidence of radial gas flows. Additional information provided by optical or near-infrared isophotes is also considered, including the relationship between the morphological and kinematic position angles. To assist in interpreting the data, we present detailed modeling that demonstrates the effects of bar streaming, inflow, and a warp on the observed Fourier components. We find in all of the galaxies evidence for either elliptical streaming or a warped disk over some range in radius, with deviations from pure circular rotation at the level of ∼20-60 km s-1. Evidence for kinematic warps is observed in several cases well inside R 25. No unambiguous evidence for radial inflows is seen in any of the seven galaxies, and we are able to place an upper limit of ∼5-10 km s -1 (3%-5% of the circular speed) on the magnitude of any radial inflow in the inner regions of NGC 4414, NGC 5033, and NGC 5055. We conclude that the inherent nonaxisymmetry of spiral galaxies is the greatest limitation to the direct detection of radial inflows.

Original languageEnglish (US)
Pages (from-to)183-204
Number of pages22
JournalAstrophysical Journal
Issue number1 I
StatePublished - Apr 10 2004
Externally publishedYes


  • Galaxies: ISM
  • Galaxies: kinematics and dynamics
  • Galaxies: spiral

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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