Velocity dispersion profiles of seven dwarf spheroidal galaxies

Matthew G. Walker, Mario Mateo, Edward W. Olszewski, Oleg Y. Gnedin, Xiao Wang, Bodhisattva Sen, Michael Woodroofe

Research output: Contribution to journalArticlepeer-review

249 Scopus citations

Abstract

We present stellar velocity dispersion profiles for seven Milky Way dwarf spheroidal (dSph) satellite galaxies. We have measured 8394 line-of-sight velocities (±2.5 km s-1) for 6804 stars from high-resolution spectra obtained at the Magellan and MMT telescopes. We combine these new data with previously published velocities to obtain the largest available kinematic samples, which include more than 5500 dSph members. All the measured dSphs have stellar velocity dispersion of order 10 km s-1 that remains approximately constant with distance from the dSph center, out to and in some cases beyond the radius at which the mean surface brightness falls to the background level. Assuming dSphs reside within dark matter halos characterized by the NFW density profile, we obtain reasonable fits to the empirical velocity dispersion profiles. These fits imply that, among the seven dSphs, Mvir ∼108-109 M. The mass enclosed at a radius of 600 pc, the region common to all data sets, lies in the range (2- 7) × 107 M.

Original languageEnglish (US)
Pages (from-to)L53-L56
JournalAstrophysical Journal
Volume667
Issue number1
DOIs
StatePublished - Sep 20 2007

Keywords

  • Dark matter
  • Galaxies: dwarf
  • Galaxies: kinematics and dynamics
  • Local Group
  • Techniques: radial velocities

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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