STELLAR VELOCITIES IN THE CARINA, FORNAX, SCULPTOR, AND SEXTANS dSph GALAXIES: DATA FROM THE MAGELLAN/MMFS SURVEY

By M. Walker, M. Mateo, E. Olszewski. 2008

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We present spectroscopic data for individual stars observed from 2004 March through 2008 August as part of our Michigan/MIKE Fiber System (MMFS) survey of four dwarf spheroidal (dSph) galaxies: Carina, Fornax, Sculptor, and Sextans. Using MMFS at the Magellan/Clay Telescope at Las Campanas Observatory, we have acquired 8855 spectra from 7103 red-giant candidates in these Galactic satellites. We list measurements of each star's line-of-sight velocity (median error ±2.1 km s−1) and spectral line indices for iron and magnesium absorption features. We use globular cluster spectra to calibrate the indices onto standard [Fe/H] metallicity scales, but comparison of the resulting metallicities with published values suggests that the MMFS indices are best used as indicators of relative, not absolute, metallicity. The empirical distributions of velocity and spectral indices also allow us to quantify the amount of contamination by foreground stars. In a companion paper, we develop an algorithm that evaluates the membership probability for each star, showing that the present MMFS sample contains more than 5000 dSph members, including 774 Carina members, 2483 Fornax members, 1365 Sculptor members, and 441 Sextans members.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/fcc2ac0c61d3701fc09939c9842664c67d67ece7

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Citations in the corpus

Formation of isolated dwarf galaxies with feedback (2009, background): “Their dynamics appear to be largely dark matter dominated, and measurements of stellar velocity dispersions (e.g. Koch et al. 2007; Walker et al. 2007; Mateo et al. 2008; Walker et al. 2009) indicate that they possess the highest mass-to-light ratios of any known galactic systems.”
The Dynamical and Chemical Evolution of Dwarf Spheroidal Galaxies with GEAR (2009, background): “The tidal and core radii are taken from Irwin & Hatzidimitriou (1995) and the velocity dispersions from Walker et al. (2009a). followed by a sharp decrease: the feedback energy acts to inhibit star formation.”
A UNIVERSAL MASS PROFILE FOR DWARF SPHEROIDAL GALAXIES? (2009, methodology): “Simon & Geha (2007) show that the ultra-faint dSphs deviate from the luminosity-M/L relation followed by the brighter dSphs (Mateo 1998), and the dynamical masses of the smallest dSphs are just ∼ 105M⊙ (e.g., Geha et al. 2009b; Walker et al. 2009a).”
Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensions (2011, methodology): “This analysis has recently been possible for the eight “classical” dSph around the Milky Way [477].”
DWARF GALAXY ANNIHILATION AND DECAY EMISSION PROFILES FOR DARK MATTER EXPERIMENTS (2014, methodology): “For Leo V, we adopt the stellar-kinematic data published by Walker et al. (2009a).”
Extragalactic science, cosmology, and Galactic archaeology with the Subaru Prime Focus Spectrograph (2012, background): “Our present investigations of the dark-matter distribution in dSphs are mostly limited to the inner regions, where abundant member stars are available from spectroscopic observations even with a small FoV (e.g., Walker et al. 2009).”
Core formation in dwarf haloes with self-interacting dark matter: no fine-tuning necessary (2014, methodology): “The points are taken from Wolf et al. (2010), who used data from Muñoz et al. (2005), Koch et al. (2007), Simon & Geha (2007), Mateo et al. (2008), and Walker et al. (2009).”
A METHOD FOR MEASURING (SLOPES OF) THE MASS PROFILES OF DWARF SPHEROIDAL GALAXIES (2011, methodology): “The MMFS data published by W09 include for each star a probability of dSph membership that is derived from an expectation-maximization (EM) algorithm (Walker et al. 2009b), similar to algorithms previously used to determine membership in open clusters (e.g., Sanders 1971).”
Accurate masses for dispersion-supported galaxies (2009, methodology): “We use 723 stellar velocities from Walker et al. (2009a) with the constraint that their membership probabilities (which are based on a combination of stellar velocity and metallicity) are greater than 0.9, and in projection they lie within 650 pc of the center (which is below the lower limit of…”
Can feedback solve the too-big-to-fail problem? (2013, methodology): “…values of the mass enclosed within the deprojected half-light radius of each of the bright dSphs around the Milky Way (computed by Wolf et al. 2010, who used data from Walker et al. 2009 in addition to data from Muñoz et al. 2005; Koch et al. 2007; Simon & Geha 2007 and Mateo et al. 2008).”
Galactic Searches for Dark Matter (2012, methodology): “…criteria to the data samples, a maximum likelihood analysis that utilizes Equation 36 provides the integrated dark matter mass within a fixed physical radius r, for an assumed parameterization for the dark matter density profile (Strigari et al., 2008; Martinez et al., 2009; Walker et al., 2009).”
Gaia DR2 proper motions of dwarf galaxies within 420 kpc (2018, methodology): “We use the catalogs of Walker et al. (2009b); Battaglia & Starkenburg (2012).”