IllustrisTNG: Universe(s) in a box
I will describe the numerical efforts to simulate galaxies across an unprecedented range of masses, environments, evolutionary stages and cosmic times. In particular, I will focus on the IllustrisTNG project ( www.tng-project.org), a series of three cosmological simulations encompassing volumes of 50, 100, and 300 Mpc a side, respectively. There gravity, magnetohydrodynamics and prescriptions for star formation, stellar evolution, the enrichment of gas with chemical elements beyond Helium, cooling and heating of the gas, galactic outflows and feedback from the supermassive black holes are all taken into account within the LCDM cosmology, i.e. the standard cosmological paradigm. In practice, in these simulations we simultaneously resolve and model the structural details of thousands of galaxies together with the large-scale cosmic web. The IllustrisTNG simulations are obtained with the moving-mesh code AREPO through field-leading computational investments of more than 100 million computing hours on thousands of computing cores and producing more than 1PB of data. In this talk, I will review our efforts to generate and effectively exploit such simulations, describe our strategies for dissemination, discuss what is explicitly and empirically solved in gravity+magnetohydrodynamics simulations for galaxy formation in a cosmological context and what is required and what it means to "successfully" reproduce populations of galaxies which resemble the real ones. Finally, I will showcase some of the insights they are allowing us to uncover and quantify. In particular, I will focus on the outcome of the final run of the series, TNG50, a cosmological volume at zoom resolution. TNG50 is allowing to reveal, for example, the quantitative details of gas outflows and their relation to galaxy properties as well as to follow the emergence of stellar and gaseous disks across cosmic times.