A Keck DEIMOS Kinematic Study of Andromeda IX: Dark Matter on the Smallest Galactic Scales

Scott C. Chapman, Rodrigo Ibata, Geraint F. Lewis, Annette M. N. Ferguson, Mike Irwin, Alan McConnachie, Nial Tanvir

Research output: Contribution to journalArticlepeer-review

Abstract

We present the results of a kinematic survey of the dwarf spheroidal satellite of M31, And IX, which appears to be the lowest surface brightness and also the faintest galaxy (MV=-8.3) found to date. Using Keck DEIMOS spectroscopic data, we have measured its velocity relative to M31, its velocity dispersion, and its metallicity. It exhibits a significant velocity dispersion σv=6.8+3.0-2.0 km s-1, which coupled with the low luminosity implies a very high mass-to-V-band light ratio, M/L~93+120-50 Msolar/Lsolar (M/L>17 Msolar/Lsolar at 99% confidence). Unless strong tidal forces have perturbed this system, this smallest of galaxies is a highly dark matter-dominated system.
Original languageEnglish
JournalAstrophysical Journal
Volume632
Issue number2
DOIs
Publication statusPublished - 1 Oct 2005

Keywords

  • Galaxies: Dwarf
  • Galaxies: Evolution
  • Galaxies: Individual: Name: Andromeda V
  • Galaxies: Individual: Name: Andromeda IX
  • Galaxies: Local Group

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