Thin disc, thick disc and halo in a simulated galaxy

C. B. Brook, G. S. Stinson, B. K. Gibson, D. Kawata, E. L. House, M. S. Miranda, Andrea Maccio, K. Pilkington, R. Roškar, J. Wadsley, T. R. Quinn

    Research output: Contribution to journalArticle

    Abstract

    Within a cosmological hydrodynamical simulation, we form a disc galaxy with sub-components which can be assigned to a thin stellar disc, thick disc and a low-mass stellar halo via a chemical decomposition. The thin- and thick-disc populations so selected are distinct in their ages, kinematics and metallicities. Thin-disc stars are young (<6.6 Gyr), possess low velocity dispersion (σ U, V, W = 41, 31, 25 kms -1), high [Fe/H] and low [O/Fe]. Conversely, the thick-disc stars are old (6.6 < age < 9.8Gyr), lag the thin disc by ∼21 kms -1, possess higher velocity dispersion (σ U, V, W = 49, 44, 35 kms -1) and have relatively low [Fe/H] and high [O/Fe]. The halo component comprises less than 4 per cent of stars in the 'solar annulus' of the simulation, has low metallicity, a velocity ellipsoid defined by σ U, V, W = 62, 46, 45 kms -1 and is formed primarily in situ during an early merger epoch. Gas-rich mergers during this epoch play a major role in fuelling the formation of the old-disc stars (the thick disc). We demonstrate that this is consistent with studies which show that cold accretion is the main source of a disc galaxy's baryons. Our simulation initially forms a relatively short (scalelength ∼1.7kpc at z = 1) and kinematically hot disc, primarily from gas accreted during the galaxy's merger epoch. Far from being a competing formation scenario, we show that migration is crucial for reconciling the short, hot, discs which form at high redshift in Λ cold dark matter, with the properties of the thick disc at z = 0. The thick disc, as defined by its abundances, maintains its relatively short scalelength at z = 0 (2.31kpc) compared with the total disc scalelength of 2.73kpc. The inside-out nature of disc growth is imprinted in the evolution of abundances such that the metal-poor α-young population has a larger scalelength (4.07kpc) than the more chemically evolved metal-rich α-young population (2.74kpc).

    Original languageEnglish (US)
    Pages (from-to)690-700
    Number of pages11
    JournalMonthly Notices of the Royal Astronomical Society
    Volume426
    Issue number1
    DOIs
    StatePublished - Oct 11 2012

    Fingerprint

    merger
    halos
    young population
    galaxies
    simulation
    metal
    gas
    kinematics
    accretion
    decomposition
    stars
    disk galaxies
    time measurement
    metallicity
    cold
    refueling
    annuli
    ellipsoids
    gases
    metals

    Keywords

    • Disc
    • Evolution
    • Formation
    • Galaxies
    • Galaxy

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    Brook, C. B., Stinson, G. S., Gibson, B. K., Kawata, D., House, E. L., Miranda, M. S., ... Quinn, T. R. (2012). Thin disc, thick disc and halo in a simulated galaxy. Monthly Notices of the Royal Astronomical Society, 426(1), 690-700. https://doi.org/10.1111/j.1365-2966.2012.21738.x

    Thin disc, thick disc and halo in a simulated galaxy. / Brook, C. B.; Stinson, G. S.; Gibson, B. K.; Kawata, D.; House, E. L.; Miranda, M. S.; Maccio, Andrea; Pilkington, K.; Roškar, R.; Wadsley, J.; Quinn, T. R.

    In: Monthly Notices of the Royal Astronomical Society, Vol. 426, No. 1, 11.10.2012, p. 690-700.

    Research output: Contribution to journalArticle

    Brook, CB, Stinson, GS, Gibson, BK, Kawata, D, House, EL, Miranda, MS, Maccio, A, Pilkington, K, Roškar, R, Wadsley, J & Quinn, TR 2012, 'Thin disc, thick disc and halo in a simulated galaxy', Monthly Notices of the Royal Astronomical Society, vol. 426, no. 1, pp. 690-700. https://doi.org/10.1111/j.1365-2966.2012.21738.x
    Brook CB, Stinson GS, Gibson BK, Kawata D, House EL, Miranda MS et al. Thin disc, thick disc and halo in a simulated galaxy. Monthly Notices of the Royal Astronomical Society. 2012 Oct 11;426(1):690-700. https://doi.org/10.1111/j.1365-2966.2012.21738.x
    Brook, C. B. ; Stinson, G. S. ; Gibson, B. K. ; Kawata, D. ; House, E. L. ; Miranda, M. S. ; Maccio, Andrea ; Pilkington, K. ; Roškar, R. ; Wadsley, J. ; Quinn, T. R. / Thin disc, thick disc and halo in a simulated galaxy. In: Monthly Notices of the Royal Astronomical Society. 2012 ; Vol. 426, No. 1. pp. 690-700.
    @article{daaac92d6a6148f7a7bb9251df029147,
    title = "Thin disc, thick disc and halo in a simulated galaxy",
    abstract = "Within a cosmological hydrodynamical simulation, we form a disc galaxy with sub-components which can be assigned to a thin stellar disc, thick disc and a low-mass stellar halo via a chemical decomposition. The thin- and thick-disc populations so selected are distinct in their ages, kinematics and metallicities. Thin-disc stars are young (<6.6 Gyr), possess low velocity dispersion (σ U, V, W = 41, 31, 25 kms -1), high [Fe/H] and low [O/Fe]. Conversely, the thick-disc stars are old (6.6 < age < 9.8Gyr), lag the thin disc by ∼21 kms -1, possess higher velocity dispersion (σ U, V, W = 49, 44, 35 kms -1) and have relatively low [Fe/H] and high [O/Fe]. The halo component comprises less than 4 per cent of stars in the 'solar annulus' of the simulation, has low metallicity, a velocity ellipsoid defined by σ U, V, W = 62, 46, 45 kms -1 and is formed primarily in situ during an early merger epoch. Gas-rich mergers during this epoch play a major role in fuelling the formation of the old-disc stars (the thick disc). We demonstrate that this is consistent with studies which show that cold accretion is the main source of a disc galaxy's baryons. Our simulation initially forms a relatively short (scalelength ∼1.7kpc at z = 1) and kinematically hot disc, primarily from gas accreted during the galaxy's merger epoch. Far from being a competing formation scenario, we show that migration is crucial for reconciling the short, hot, discs which form at high redshift in Λ cold dark matter, with the properties of the thick disc at z = 0. The thick disc, as defined by its abundances, maintains its relatively short scalelength at z = 0 (2.31kpc) compared with the total disc scalelength of 2.73kpc. The inside-out nature of disc growth is imprinted in the evolution of abundances such that the metal-poor α-young population has a larger scalelength (4.07kpc) than the more chemically evolved metal-rich α-young population (2.74kpc).",
    keywords = "Disc, Evolution, Formation, Galaxies, Galaxy",
    author = "Brook, {C. B.} and Stinson, {G. S.} and Gibson, {B. K.} and D. Kawata and House, {E. L.} and Miranda, {M. S.} and Andrea Maccio and K. Pilkington and R. Roškar and J. Wadsley and Quinn, {T. R.}",
    year = "2012",
    month = "10",
    day = "11",
    doi = "10.1111/j.1365-2966.2012.21738.x",
    language = "English (US)",
    volume = "426",
    pages = "690--700",
    journal = "Monthly Notices of the Royal Astronomical Society",
    issn = "0035-8711",
    publisher = "Oxford University Press",
    number = "1",

    }

    TY - JOUR

    T1 - Thin disc, thick disc and halo in a simulated galaxy

    AU - Brook, C. B.

    AU - Stinson, G. S.

    AU - Gibson, B. K.

    AU - Kawata, D.

    AU - House, E. L.

    AU - Miranda, M. S.

    AU - Maccio, Andrea

    AU - Pilkington, K.

    AU - Roškar, R.

    AU - Wadsley, J.

    AU - Quinn, T. R.

    PY - 2012/10/11

    Y1 - 2012/10/11

    N2 - Within a cosmological hydrodynamical simulation, we form a disc galaxy with sub-components which can be assigned to a thin stellar disc, thick disc and a low-mass stellar halo via a chemical decomposition. The thin- and thick-disc populations so selected are distinct in their ages, kinematics and metallicities. Thin-disc stars are young (<6.6 Gyr), possess low velocity dispersion (σ U, V, W = 41, 31, 25 kms -1), high [Fe/H] and low [O/Fe]. Conversely, the thick-disc stars are old (6.6 < age < 9.8Gyr), lag the thin disc by ∼21 kms -1, possess higher velocity dispersion (σ U, V, W = 49, 44, 35 kms -1) and have relatively low [Fe/H] and high [O/Fe]. The halo component comprises less than 4 per cent of stars in the 'solar annulus' of the simulation, has low metallicity, a velocity ellipsoid defined by σ U, V, W = 62, 46, 45 kms -1 and is formed primarily in situ during an early merger epoch. Gas-rich mergers during this epoch play a major role in fuelling the formation of the old-disc stars (the thick disc). We demonstrate that this is consistent with studies which show that cold accretion is the main source of a disc galaxy's baryons. Our simulation initially forms a relatively short (scalelength ∼1.7kpc at z = 1) and kinematically hot disc, primarily from gas accreted during the galaxy's merger epoch. Far from being a competing formation scenario, we show that migration is crucial for reconciling the short, hot, discs which form at high redshift in Λ cold dark matter, with the properties of the thick disc at z = 0. The thick disc, as defined by its abundances, maintains its relatively short scalelength at z = 0 (2.31kpc) compared with the total disc scalelength of 2.73kpc. The inside-out nature of disc growth is imprinted in the evolution of abundances such that the metal-poor α-young population has a larger scalelength (4.07kpc) than the more chemically evolved metal-rich α-young population (2.74kpc).

    AB - Within a cosmological hydrodynamical simulation, we form a disc galaxy with sub-components which can be assigned to a thin stellar disc, thick disc and a low-mass stellar halo via a chemical decomposition. The thin- and thick-disc populations so selected are distinct in their ages, kinematics and metallicities. Thin-disc stars are young (<6.6 Gyr), possess low velocity dispersion (σ U, V, W = 41, 31, 25 kms -1), high [Fe/H] and low [O/Fe]. Conversely, the thick-disc stars are old (6.6 < age < 9.8Gyr), lag the thin disc by ∼21 kms -1, possess higher velocity dispersion (σ U, V, W = 49, 44, 35 kms -1) and have relatively low [Fe/H] and high [O/Fe]. The halo component comprises less than 4 per cent of stars in the 'solar annulus' of the simulation, has low metallicity, a velocity ellipsoid defined by σ U, V, W = 62, 46, 45 kms -1 and is formed primarily in situ during an early merger epoch. Gas-rich mergers during this epoch play a major role in fuelling the formation of the old-disc stars (the thick disc). We demonstrate that this is consistent with studies which show that cold accretion is the main source of a disc galaxy's baryons. Our simulation initially forms a relatively short (scalelength ∼1.7kpc at z = 1) and kinematically hot disc, primarily from gas accreted during the galaxy's merger epoch. Far from being a competing formation scenario, we show that migration is crucial for reconciling the short, hot, discs which form at high redshift in Λ cold dark matter, with the properties of the thick disc at z = 0. The thick disc, as defined by its abundances, maintains its relatively short scalelength at z = 0 (2.31kpc) compared with the total disc scalelength of 2.73kpc. The inside-out nature of disc growth is imprinted in the evolution of abundances such that the metal-poor α-young population has a larger scalelength (4.07kpc) than the more chemically evolved metal-rich α-young population (2.74kpc).

    KW - Disc

    KW - Evolution

    KW - Formation

    KW - Galaxies

    KW - Galaxy

    UR - http://www.scopus.com/inward/record.url?scp=84866534493&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=84866534493&partnerID=8YFLogxK

    U2 - 10.1111/j.1365-2966.2012.21738.x

    DO - 10.1111/j.1365-2966.2012.21738.x

    M3 - Article

    VL - 426

    SP - 690

    EP - 700

    JO - Monthly Notices of the Royal Astronomical Society

    JF - Monthly Notices of the Royal Astronomical Society

    SN - 0035-8711

    IS - 1

    ER -