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arXiv · 1902.05553

First Results from the TNG50 Simulation: The evolution of stellar and gaseous disks across cosmic time

Annalisa Pillepich·Dylan Nelson·Volker Springel·Ruediger Pakmor·Paul Torrey·Rainer Weinberger·Mark Vogelsberger·Federico Marinacci·Shy Genel·Arjen van der Wel·Lars Hernquist
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Abstract

We present a new cosmological, magnetohydrodynamical simulation for galaxy formation: TNG50, the third and final installment of the IllustrisTNG project. TNG50 evolves 2x2160^3 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 8.5x10^4 Msun and an average cell size of 70-140 parsecs in the star-forming regions of galaxies. Simultaneously, TNG50 samples ~700 (6,500) galaxies with stellar masses above 10^10 (10^8) Msun 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, disk heights, 3D shapes, and degree of rotational vs. dispersion-supported motions as traced by rest-frame V-band light (i.e. roughly stellar mass) and by Halpha 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 disk 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 disk-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 Msun star-forming galaxies are rotationally-supported disks for most cosmic epochs (Vmax/sigma>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.

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Annalisa Pillepich, Dylan Nelson, Volker Springel, Ruediger Pakmor, Paul Torrey, Rainer Weinberger, Mark Vogelsberger, Federico Marinacci, Shy Genel, Arjen van der Wel, Lars Hernquist. 2019-09-09. First Results from the TNG50 Simulation: The evolution of stellar and gaseous disks across cosmic time. https://doi.org/10.1093/mnras%2Fstz2338

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