CHEMICAL EVOLUTION IN HIERARCHICAL MODELS OF COSMIC STRUCTURE. II. THE FORMATION OF THE MILKY WAY STELLAR HALO AND THE DISTRIBUTION OF THE OLDEST STARS

By Jason Tumlinson. 2009

144 citations recorded by the source corpus.

This paper presents theoretical star formation and chemical enrichment histories for the stellar halo of the Milky Way (MW) based on new chemodynamical modeling. The goal of this study is to assess the extent to which metal-poor stars in the halo reflect the star formation conditions that occurred in halo progenitor galaxies at high redshift, before, and during the epoch of re-ionization. Simple prescriptions that translate dark-matter (DM) halo mass into baryonic gas budgets and star formation histories yield models that resemble the observed MW halo in its total stellar mass, metallicity distribution, and the luminosity function and chemical enrichment of dwarf satellite galaxies. These model halos in turn allow an exploration of how the populations of interest for probing the epoch of re-ionization are distributed in physical and phase space, and of how they are related to lower-redshift populations of the same metallicity. The fraction of stars dating from before a particular time or redshift depends strongly on radius within the galaxy, reflecting the “inside-out” growth of cold DM halos, and on metallicity, reflecting the general trend toward higher metallicity at later times. These results suggest that efforts to discover stars from z>6–10 should select for stars with [Fe/H] ≲−3 and favor stars on more tightly bound orbits in the stellar halo, where the majority are from z>10 and 15%–40% are from z>15. The oldest, most metal-poor stars—those most likely to reveal the chemical abundances of the first stars—are most common in the very center of the Galaxy's halo: they are in the bulge, but not of the bulge. These models have several implications for the larger project of constraining the properties of the first stars and galaxies using data from the local universe.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/8a65379aaf8cf8049850d371bcad4341d63e0541

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Citations in the corpus

• The Apache Point Observatory Galactic Evolution Experiment (APOGEE) (2007, unknown): “To contribute to explorations of the early Galaxy by inferring the properties of the earliest stars, thought to reside or to have resided in the Galactic bulge (Tumlinson 2010).”
• THE LONG-TERM EVOLUTION OF THE GALACTIC DISK TRACED BY DISSOLVING STAR CLUSTERS (2010, background): “Some of these systems may even carry the hallmarks of the first generations of stars in the early universe (Tumlinson 2010).”
• ARGOS – IV. The kinematics of the Milky Way bulge (2013, background): “According toΛCDM simulations, the bulge region between longitudes of 10◦ to 20◦ is expected to contain the oldest stars in the Galaxy, likely only a few generations older than the first stars (Tumlinson 2010).”
• ARGOS - III. Stellar populations in the Galactic bulge of the Milky Way (2012, background): “Simulations (e.g. Diemand, Madau, & Moore 2005; Brook et al. 2007; Tumlinson 2010) show that the oldest stars in the Galaxy, formed in fragments from high-σ density fluctuations, should now inhabit the inner Galaxy.”
• ONE HUNDRED FIRST STARS: PROTOSTELLAR EVOLUTION AND THE FINAL MASSES (2013, background): “The current survey of metal-poor stars are targeted halo stars, whereas most of the remnants of the first stars could be concentrated toward the central regions of the Galaxy (White & Springel 2000; Tumlinson 2010).”
• Near-Field Cosmology with Extremely Metal-Poor Stars (2015, background): “While its oldest stars formed coevally with the early assembly phases of the Milky Way (e.g., Brook et al. 2007, Tumlinson 2010), several younger populations are also present, making it chal- lenging to efficiently isolate individual members of the first population.”
• THE BIRTH OF A GALAXY: PRIMORDIAL METAL ENRICHMENT AND STELLAR POPULATIONS (2010, methodology): “…semi-analytic models (Scannapieco et al. 2003; Yoshida et al. 2004; Furlanetto & Loeb 2005), (ii) models using hierarchical merger trees (Tumlinson 2006, 2010; Salvadori et al. 2007; Komiya et al. 2010), (iii) post-processing of cosmological simulations with blastwave models (Karlsson…”
• THE SPECTRAL EVOLUTION OF THE FIRST GALAXIES. I. JAMES WEBB SPACE TELESCOPE DETECTION LIMITS AND COLOR CRITERIA FOR POPULATION III GALAXIES (2011, background): “The stars bearing the mark of such supernovae may be too scarce (e.g. Salvadori et al. 2007; Trenti & Shull 2010), hiding at too high metallicities (Karlsson et al. 2008) or in the inner regions of the Galaxy (e.g. Tumlinson 2010).”
• THE QUENCHING OF THE ULTRA-FAINT DWARF GALAXIES IN THE REIONIZATION ERA (2014, background): “…formation in the smallest DM sub-halos QUENCHING OF THEULTRA-FAINT DWARF GALAXIES 11 (e.g., Bullock et al. 2001; Ricotti & Gnedin 2005; Muñoz et al. 2009; Bovill & Ricotti 2009, 2011a, 2011b; Tumlinson 2010; Koposov et al. 2009; Li et al. 2010; Salvadori & Ferrara 2009; Salvadori et al. 2014).”
• Chemical tagging with APOGEE: Discovery of a large population of N-rich stars in the inner Galaxy (2016, background): “Some numerical simulations predict that the oldest stars in the Galaxy are indeed to be found in its central regions (e.g., Brook et al. 2007; Tumlinson 2010).”