NIHAO XVI: The properties and evolution of kinematically selected discs, bulges, and stellar haloes

Aura Obreja, Aaron A. Dutton, Andrea Maccio, Benjamin Moster, Tobias Buck, Glenn Van Den Ven, Liang Wang, Gregory S. Stinson, Ling Zhu

Research output: Contribution to journalArticle

Abstract

We use 25 simulated galaxies from the NIHAO project to define and characterize a variety of kinematic stellar structures: Thin and thick discs, large-scale single discs, classical and pseudobulges, spheroids, inner discs, and stellar haloes. These structures have masses, spins, shapes, and rotational support in good agreement with theoretical expectations and observational data. Above a dark matter halo mass of 2.5 × 1011Mθ, all galaxies have a classical bulge and 70 per cent have a thin and thick disc. The kinematic (thin) discs follow a power-law relation between angular momentum and stellarmass J= 3.4M1.26±0.06, in very good agreement with the prediction based on the empirical stellar-to-halo-mass relation in the same mass range, and show a strong correlation between maximum 'observed' rotation velocity and dark matter halo circular velocity vc = 6.4v0.64±0.04 max . Tracing back in time these structures' progenitors, we find all of them to lose a fraction 1 - fj of their maximum angular momentum. Thin discs are significantly better at retaining their high-redshift spins (fj ∼ 0.70) than thick ones (fj ∼ 0.40). Stellar haloes have their progenitor baryons assembled the latest (z1/2 ∼ 1.1) and over the longest time-scales (τ ∼ 6.2Gyr), and have the smallest fraction of stars born in situ (fin situ = 0.35 ± 0.14). All other structures have 1.5 ≲ z1/2 ≲ 3, τ = 4 ± 2Gyr, and fin situ ≳ 0.9.

Original languageEnglish (US)
Pages (from-to)4424-4456
Number of pages33
JournalMonthly Notices of the Royal Astronomical Society
Volume487
Issue number3
DOIs
StatePublished - Jan 1 2019

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halos
angular momentum
kinematics
fins
dark matter
galaxies
stellar structure
power law
spheroids
tracing
retaining
timescale
baryons
prediction
stars
predictions

Keywords

  • Galaxies: Fundamental parameters
  • Galaxies: Kinematics and dynamics
  • Galaxies: Stellar content
  • Galaxies: Structure
  • Methods: numerical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

NIHAO XVI : The properties and evolution of kinematically selected discs, bulges, and stellar haloes. / Obreja, Aura; Dutton, Aaron A.; Maccio, Andrea; Moster, Benjamin; Buck, Tobias; Van Den Ven, Glenn; Wang, Liang; Stinson, Gregory S.; Zhu, Ling.

In: Monthly Notices of the Royal Astronomical Society, Vol. 487, No. 3, 01.01.2019, p. 4424-4456.

Research output: Contribution to journalArticle

Obreja, A, Dutton, AA, Maccio, A, Moster, B, Buck, T, Van Den Ven, G, Wang, L, Stinson, GS & Zhu, L 2019, 'NIHAO XVI: The properties and evolution of kinematically selected discs, bulges, and stellar haloes', Monthly Notices of the Royal Astronomical Society, vol. 487, no. 3, pp. 4424-4456. https://doi.org/10.1093/mnras/stz1563
Obreja, Aura ; Dutton, Aaron A. ; Maccio, Andrea ; Moster, Benjamin ; Buck, Tobias ; Van Den Ven, Glenn ; Wang, Liang ; Stinson, Gregory S. ; Zhu, Ling. / NIHAO XVI : The properties and evolution of kinematically selected discs, bulges, and stellar haloes. In: Monthly Notices of the Royal Astronomical Society. 2019 ; Vol. 487, No. 3. pp. 4424-4456.
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T2 - The properties and evolution of kinematically selected discs, bulges, and stellar haloes

AU - Obreja, Aura

AU - Dutton, Aaron A.

AU - Maccio, Andrea

AU - Moster, Benjamin

AU - Buck, Tobias

AU - Van Den Ven, Glenn

AU - Wang, Liang

AU - Stinson, Gregory S.

AU - Zhu, Ling

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N2 - We use 25 simulated galaxies from the NIHAO project to define and characterize a variety of kinematic stellar structures: Thin and thick discs, large-scale single discs, classical and pseudobulges, spheroids, inner discs, and stellar haloes. These structures have masses, spins, shapes, and rotational support in good agreement with theoretical expectations and observational data. Above a dark matter halo mass of 2.5 × 1011Mθ, all galaxies have a classical bulge and 70 per cent have a thin and thick disc. The kinematic (thin) discs follow a power-law relation between angular momentum and stellarmass J= 3.4M1.26±0.06, in very good agreement with the prediction based on the empirical stellar-to-halo-mass relation in the same mass range, and show a strong correlation between maximum 'observed' rotation velocity and dark matter halo circular velocity vc = 6.4v0.64±0.04 max . Tracing back in time these structures' progenitors, we find all of them to lose a fraction 1 - fj of their maximum angular momentum. Thin discs are significantly better at retaining their high-redshift spins (fj ∼ 0.70) than thick ones (fj ∼ 0.40). Stellar haloes have their progenitor baryons assembled the latest (z1/2 ∼ 1.1) and over the longest time-scales (τ ∼ 6.2Gyr), and have the smallest fraction of stars born in situ (fin situ = 0.35 ± 0.14). All other structures have 1.5 ≲ z1/2 ≲ 3, τ = 4 ± 2Gyr, and fin situ ≳ 0.9.

AB - We use 25 simulated galaxies from the NIHAO project to define and characterize a variety of kinematic stellar structures: Thin and thick discs, large-scale single discs, classical and pseudobulges, spheroids, inner discs, and stellar haloes. These structures have masses, spins, shapes, and rotational support in good agreement with theoretical expectations and observational data. Above a dark matter halo mass of 2.5 × 1011Mθ, all galaxies have a classical bulge and 70 per cent have a thin and thick disc. The kinematic (thin) discs follow a power-law relation between angular momentum and stellarmass J= 3.4M1.26±0.06, in very good agreement with the prediction based on the empirical stellar-to-halo-mass relation in the same mass range, and show a strong correlation between maximum 'observed' rotation velocity and dark matter halo circular velocity vc = 6.4v0.64±0.04 max . Tracing back in time these structures' progenitors, we find all of them to lose a fraction 1 - fj of their maximum angular momentum. Thin discs are significantly better at retaining their high-redshift spins (fj ∼ 0.70) than thick ones (fj ∼ 0.40). Stellar haloes have their progenitor baryons assembled the latest (z1/2 ∼ 1.1) and over the longest time-scales (τ ∼ 6.2Gyr), and have the smallest fraction of stars born in situ (fin situ = 0.35 ± 0.14). All other structures have 1.5 ≲ z1/2 ≲ 3, τ = 4 ± 2Gyr, and fin situ ≳ 0.9.

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KW - Galaxies: Kinematics and dynamics

KW - Galaxies: Stellar content

KW - Galaxies: Structure

KW - Methods: numerical

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