First results from the TNG50 simulation: the evolution of stellar and gaseous discs across cosmic time

By A. Pillepich, D. Nelson, Volker Springel, Rüdiger Pakmor, P. Torrey, R. Weinberger, M. Vogelsberger, F. Marinacci, Shy Genel, Arjen van der Wel and 1 more. Monthly notices of the Royal Astronomical Society, 2019

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We present a new cosmological, magnetohydrodynamical simulation for galaxy formation: TNG50, the third and final instalment of the IllustrisTNG project. TNG50 evolves 2 × 21603 dark matter particles and gas cells in a volume 50 comoving Mpc across. It hence reaches a numerical resolution typical of zoom-in simulations, with a baryonic element mass of $8.5\times 10^4\, {\rm M}_{\odot }$ and an average cell size of 70–140 pc in the star-forming regions of galaxies. Simultaneously, TNG50 samples ∼700 (6500) galaxies with stellar masses above $10^{10} \, (10^8)\, {\rm M}_{\odot }$ at $z$ = 1. Here we investigate the structural and kinematical evolution of star-forming galaxies across cosmic time (0 ≲ $z$ ≲ 6). We quantify their sizes, disc heights, 3D shapes, and degree of rotational versus dispersion-supported motions as traced by rest-frame V-band light (i.e. roughly stellar mass) and by $\rm H\,\alpha$ light (i.e. star-forming and dense gas). The unprecedented resolution of TNG50 enables us to model galaxies with sub-kpc half-light radii and with ≲300-pc disc heights. Coupled with the large-volume statistics, we characterize a diverse, redshift- and mass-dependent structural and kinematical morphological mix of galaxies all the way to early epochs. Our model predicts that for star-forming galaxies the fraction of disc-like morphologies, based on 3D stellar shapes, increases with both cosmic time and galaxy stellar mass. Gas kinematics reveal that the vast majority of $10^{9-11.5}\, {\rm M}_{\odot }$ star-forming galaxies are rotationally supported discs for most cosmic epochs (Vrot/σ > 2–3, $z$ ≲ 5), being dynamically hotter at earlier epochs ($z$ ≳ 1.5). Despite large velocity dispersion at high redshift, cold and dense gas in galaxies predominantly arranges in disky or elongated shapes at all times and masses; these gaseous components exhibit rotationally dominated motions far exceeding the collisionless stellar bodies.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/341d9463cf7b06f558c7212807108c34efc304e0

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Citations in the corpus

The IllustrisTNG simulations: public data release (2018, background): “The ﬂagship volumes of the IllustrisTNG—TNG50, TNG100, and TNG300—are accompanied by an additional resource: a large number of ‘TNG Model Variation’ simulations.”