NIHAO XVI: the properties and evolution of kinematically selected discs, bulges, and stellar haloes
| Autor: | G. S. Stinson, Andrea V. Macciò, Ling Zhu, Liang Wang, Glenn Van Den Ven, Tobias Buck, Benjamin P. Moster, Aaron A. Dutton, Aura Obreja |
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| Rok vydání: | 2019 |
| Předmět: |
Physics
Angular momentum Spins Stellar mass 010308 nuclear & particles physics FOS: Physical sciences Astronomy and Astrophysics Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics 01 natural sciences Astrophysics - Astrophysics of Galaxies Galaxy Baryon Dark matter halo Stars Space and Planetary Science Bulge Astrophysics of Galaxies (astro-ph.GA) 0103 physical sciences Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics 010303 astronomy & astrophysics Astrophysics::Galaxy Astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society |
| Popis: | 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 pseudo bulges, 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 $2.5\times10^{\rm~11}M_{\rm\odot}$, all galaxies have a classical bulge and 70\% have a thin and thick disc. The kinematic (thin) discs follow a power-law relation between angular momentum and stellar mass $J_{\rm *}=3.4M_{\rm *}^{\rm1.26\pm0.06}$, 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 $v_{\rm c}=6.4v_{\rm max}^{0.64\pm0.04}$. Tracing back in time these structures' progenitors, we find all to lose a fraction $1-f_j$ of their maximum angular momentum. Thin discs are significantly better at retaining their high-redshift spins ($f_j\sim0.70$) than thick ones ($f_j\sim0.40$). Stellar haloes have their progenitor baryons assembled the latest ($z_{\rm~1/2}\sim1.1$) and over the longest timescales ($\tau\sim6.2$~Gyr), and have the smallest fraction of stars born in-situ ($f_{\rm in-situ}=0.35\pm0.14$). All other structures have $1.5\lesssim z_{\rm1/2}\lesssim3$, $\tau=4\pm2$~Gyr and $f_{\rm in-situ}\gtrsim0.9$. Comment: Accepted by MNRAS. First application of the methods described in arXiv:1804.05576 |
| Databáze: | OpenAIRE |
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