Stars behind Bars. I. the Milky Way's Central Stellar Populations

Tobias Buck, Melissa K. Ness, Andrea Maccio, Aura Obreja, Aaron A. Dutton

    Research output: Contribution to journalArticle

    Abstract

    We show for the first time that a fully cosmological hydrodynamical simulation can reproduce key properties of the innermost region of the Milky Way (MW). Our high-resolution simulation reproduces qualitatively the profile and kinematics of the MW's boxy/peanut-shaped bulge, and hence we can use it to reconstruct and understand the bulge assembly. In particular, the age dependence of the X-shape morphology of the simulated bulge parallels the observed metallicity-dependent split in the red clump stars of the inner Galaxy. We use this feature to propose an observational metric that (after calibrated against a larger set of simulations) might allow us to quantify when the bulge formed from the disk. The metric we propose can be employed with upcoming survey data to constrain the age of the MW bar. From the split in stellar counts we estimate the formation of the 4 kpc scale bar in the simulation to have happened Gyr ago, in good agreement with conventional methods to measure bar formation in simulations. We test the prospects for observationally differentiating the stars that belong to the bulge/bar compared to the surrounding disk, and we find that the inner disk and bulge are practically indistinguishable in both chemistry and ages.

    Original languageEnglish (US)
    Article number88
    JournalAstrophysical Journal
    Volume861
    Issue number2
    DOIs
    StatePublished - Jul 10 2018

    Fingerprint

    stars
    simulation
    clumps
    metallicity
    kinematics
    assembly
    chemistry
    galaxies
    high resolution
    estimates
    profiles

    Keywords

    • dark matter
    • galaxies: bulges
    • galaxies: formation
    • galaxies: individual (Milky Way)
    • galaxies: kinematics and dynamics
    • methods: numerical

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    Buck, T., Ness, M. K., Maccio, A., Obreja, A., & Dutton, A. A. (2018). Stars behind Bars. I. the Milky Way's Central Stellar Populations. Astrophysical Journal, 861(2), [88]. https://doi.org/10.3847/1538-4357/aac890

    Stars behind Bars. I. the Milky Way's Central Stellar Populations. / Buck, Tobias; Ness, Melissa K.; Maccio, Andrea; Obreja, Aura; Dutton, Aaron A.

    In: Astrophysical Journal, Vol. 861, No. 2, 88, 10.07.2018.

    Research output: Contribution to journalArticle

    Buck, T, Ness, MK, Maccio, A, Obreja, A & Dutton, AA 2018, 'Stars behind Bars. I. the Milky Way's Central Stellar Populations', Astrophysical Journal, vol. 861, no. 2, 88. https://doi.org/10.3847/1538-4357/aac890
    Buck, Tobias ; Ness, Melissa K. ; Maccio, Andrea ; Obreja, Aura ; Dutton, Aaron A. / Stars behind Bars. I. the Milky Way's Central Stellar Populations. In: Astrophysical Journal. 2018 ; Vol. 861, No. 2.
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