Exploring Halo Substructure with Giant Stars: The Velocity Dispersion Profiles of the Ursa Minor and Draco Dwarf Spheroidals At Large Angular Separations

Abstract

We analyze velocity dispersion profiles for the Draco and Ursa Minor (UMi) dwarf spheroidal (dSph) galaxies based on published and new Keck HIRES spectra for stars in the outer UMi field. Washington+DDO51 filter photometric catalogs provide additional leverage on membership of individual stars, and beyond 0.5 King limiting radii (R_lim) identify bona fide dSph members up to 4.5 times more efficiently than simple color-magnitude diagram selections. Previously reported ``cold populations'' R_lim are not obvious in the data and appear only with particular binning; more or less constant and platykurtic dispersion profiles are characteristic of these dSphs to large radii. We report discovery of UMi stars to at least 2.7 R_lim (i.e.,210 arcmin or 4 kpc). Even with conservative assumptions, a UMi mass of M > 4.9 x 10^8 M_(sun) is required to bind these stars, implying an unlikely global mass-to-light ratio of M/L > 900 (M/L)_(sun). We conclude that we have found stars tidally stripped from UMi.

9 pages, 4 figures. Published in the Astrophysical Journal Letters

References in corpus (22)

• Dark Matter Substructure in Galactic Halos
• Where are the missing galactic satellites?
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: I. Morphology of the Sagittarius Core and Tidal Arms
• The Structural Evolution of Substructure
• Two distinct ancient components in the Sculptor Dwarf Spheroidal Galaxy: First Results from DART
• The Milky Way's satellite population in a LambdaCDM universe
• Dark Matter in Dwarf Spheroidals II: Observations and Modelling of Draco
• Kinematically Cold Populations at Large Radii in the Draco and Ursa Minor Dwarf Spheroidals
• A Two Micron All-Sky Survey View of the Sagittarius Dwarf Galaxy: II. Swope Telescope Spectroscopy of M Giant Stars in the Dynamically Cold Sagittarius Tidal Stream
• Exploring Halo Substructure with Giant Stars: I. Survey Description and Calibration of the Photometric Search Technique
• Dark matter distribution in dwarf spheroidal galaxies
• Exploring Halo Substructure with Giant Stars IV: The Extended Structure of the Ursa Minor Dwarf Spheroidal
• New insights on the Draco dwarf spheroidal galaxy from SDSS: a larger radius and no tidal tails
• Dark Matter in Dwarf Spheroidals I: Models
• Exploring Halo Substructure with Giant Stars: II. Mapping the Extended Structure of the Carina Dwarf Spheroidal Galaxy
• Tidal debris of dwarf spheroidals as a probe of structure formation models
• A photometrically and kinematically distinct core in the Sextans dwarf spheroidal galaxy
• A tidal extension in the Ursa Minor dwarf spheroidal galaxy
• Blue horizontal branch stars in the Sloan Digital Sky Survey: II. Kinematics of the Galactic halo
• Do dwarf spheroidal galaxies contain dark matter?
• Parametric Dwarf Spheroidal Tidal Interaction
• A new method of estimating the mass-to-light ratio of the Ursa Minor dwarf spheroidal galaxy

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