MULTI-ELEMENT ABUNDANCE MEASUREMENTS FROM MEDIUM-RESOLUTION SPECTRA. III. METALLICITY DISTRIBUTIONS OF MILKY WAY DWARF SATELLITE GALAXIES

By E. Kirby, G. Lanfranchi, J. Simon, J. Cohen, P. Guhathakurta. 2010

224 citations recorded by the source corpus.

We present metallicity distribution functions (MDFs) for the central regions of eight dwarf satellite galaxies of the Milky Way: Fornax, Leo I and II, Sculptor, Sextans, Draco, Canes Venatici I, and Ursa Minor. We use the published catalog of abundance measurements from the previous paper in this series. The measurements are based on spectral synthesis of iron absorption lines. For each MDF, we determine maximum likelihood fits for Leaky Box, Pre-Enriched, and Extra Gas (wherein the gas supply available for star formation increases before it decreases to zero) analytic models of chemical evolution. Although the models are too simplistic to describe any MDF in detail, a Leaky Box starting from zero metallicity gas fits none of the galaxies except Canes Venatici I well. The MDFs of some galaxies, particularly the more luminous ones, strongly prefer the Extra Gas Model to the other models. Only for Canes Venatici I does the Pre-Enriched Model fit significantly better than the Extra Gas Model. The best-fit effective yields of the less luminous half of our galaxy sample do not exceed 0.02 Z☉, indicating that gas outflow is important in the chemical evolution of the less luminous galaxies. We surmise that the ratio of the importance of gas infall to gas outflow increases with galaxy luminosity. Strong correlations of average [Fe/H] and metallicity spread with luminosity support this hypothesis.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/00701242a8299c4e543ef1370589587d52fd87db

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Citations in the corpus

METALLICITY EVOLUTION OF DAMPED Lyα SYSTEMS OUT TO z ∼ 5 (2012, background): “Such low metallicity stars are even now seen in more massive dwarf spheroidal galaxies (Kirby et al. 2011b).”
The birth of a galaxy – II. The role of radiation pressure (2012, background): “…a fraction of high-redshift galaxies survive until the presentday (Gnedin & Kravtsov 2006; Bovill & Ricotti 2011), then the bounds of MDFs should not exceed the ones observed in local dwarf galaxies, which typically have most of their stars within the range –3 < [Fe/H] < –1 (Kirby et al. 2011).”
Star formation in semi-analytic galaxy formation models with multiphase gas (2015, background): “Note that observations of resolved stars in the halo of our Galaxy and local dwarfs have revealed stars with metallicities below Z ∼ 10−3 Z⊙ (Tolstoy et al. 2009; Schörck et al. 2009; Kirby et al. 2011), precluding much higher values for Zpre−enrich.”
The bifurcated age–metallicity relation of Milky Way globular clusters and its implications for the accretion history of the galaxy (2013, background): “The offset in the GC AMR is approximately 0.6 dex in metallicity, which, given the slope of the MMR3 (Tremonti et al. 2004; Gallazzi et al. 2005; Lee et al. 2006; Kirby et al. 2011), translates into a difference in stellar mass of approximately ∆ log M∗ ∼ 2 dex.”
A COMPLETE SPECTROSCOPIC SURVEY OF THE MILKY WAY SATELLITE SEGUE 1: THE DARKEST GALAXY (2010, background): “An alternative possibility is that the stream might be related to Leo I, which is located approximately 3.8◦ due south of Segue 1 at a similar velocity (282.9 ± 0.5 km s−1; Mateo, Olszewski, & Walker 2008) and metallicity ([Fe/H] = −1.20; Kirby et al. 2011).”
THE COUPLING BETWEEN THE CORE/CUSP AND MISSING SATELLITE PROBLEMS (2012, background): “Recently, Revaz & Jablonka (2012) argue that ǫSN ≈ 0.05 in order to describe the relation between metallicity and luminosity found in dSphs (e.g. Kirby et al. 2011).”
THE UNIVERSAL STELLAR MASS–STELLAR METALLICITY RELATION FOR DWARF GALAXIES (2013, methodology): “If the gradients that Kirby et al. (2011a) and Battaglia et al. (2011) measured persist out the tidal radii, then the typical bias in 〈[Fe/H]〉 caused by the central concentration of our spectroscopic sample is .”
The Dynamical and Chemical Evolution of Dwarf Spheroidal Galaxies with GEAR (2009, background): “Kirby et al. (2011) reported shallow metallicity gradients of at most −0.21 dex per core radius in LeoII .”
A KINEMATIC STUDY OF THE ANDROMEDA DWARF SPHEROIDAL SYSTEM (2013, methodology): “We plot the MW dSphs as red triangles (Martin et al. 2007; Kirby et al. 2008, 2011; Belokurov et al. 2009; Koch et al. 2009).”
Near-Field Cosmology with Extremely Metal-Poor Stars (2015, background): “• Considering the populations of both dSph and ultra-faint dwarfs, it has been shown that as one goes to fainter luminosities in these systems the mean value of [Fe/H] decreases while its dispersion increases (Kirby et al. 2008, Norris et al. 2010b, Kirby et al. 2011, Leaman 2012).”
THE STELLAR INITIAL MASS FUNCTION OF ULTRA-FAINT DWARF GALAXIES: EVIDENCE FOR IMF VARIATIONS WITH GALACTIC ENVIRONMENT (2013, methodology): “For the fixed single age of each UFD, we linearly combine tracks for different metallicities to recreate the spectroscopic metallicity distribution function (MDF) as determined by Kirby et al. (2011) based on Keck/DEIMOS data from Simon & Geha (2007).”
BREATHING FIRE: HOW STELLAR FEEDBACK DRIVES RADIAL MIGRATION, RAPID SIZE FLUCTUATIONS, AND POPULATION GRADIENTS IN LOW-MASS GALAXIES (2015, background): “Several studies (for example, Mehlert et al. 2003; Spolaor et al. 2009; Kirby et al. 2011; Schroyen et al. 2013; Vargas et al. 2014; Pilyugin et al. 2015) find an average metallicity gradient of ∆[Fe/H] ∼ −0.4 dex between the galactic center and the effective radius, but with significant (∼ 0.3…”
THE QUENCHING OF THE ULTRA-FAINT DWARF GALAXIES IN THE REIONIZATION ERA (2014, methodology): “Observations Metallicities for limited samples of stars in five of the six UFDs targeted withHST were determined by Kirby et al. (2008), Kirby et al. (2011), and Vargas et al. (2013), based on the medium-resolution (1.37 Å FWHM)Keck spectroscopy of Simon & Geha (2007).”