The IllustrisTNG Simulations: Public Data Release

TL;DR

IllustrisTNG publicly releases three large cosmological volumes (TNG50, TNG100, TNG300) with full snapshots, group catalogs, merger trees, and high-time-resolution subboxes, enabling broad exploration of galaxy formation in a ΛCDM context. The release integrates flexible data access via direct downloads, a feature-rich web API, and an online JupyterLab environment to analyze data remotely, reducing the need to download voluminous datasets. Methodologically, the paper details the physics implemented (cooling, star formation, feedback, magnetic fields) and the numerical framework (Arepo, MHD, Subfind, SubLink/LHaloTree), and it discusses validation, caveats, and observational tensions to guide robust science. Overall, this work provides a comprehensive, accessible ecosystem for community-driven science, with plans for additional data products, dashboards, and catalogs to extend the utility of IllustrisTNG findings.

Abstract

We present the full public release of all data from the TNG50, TNG100 and TNG300 simulations of the IllustrisTNG project. IllustrisTNG is a suite of large volume, cosmological, gravo-magnetohydrodynamical simulations run with the moving-mesh code Arepo. TNG includes a comprehensive model for galaxy formation physics, and each TNG simulation self-consistently solves for the coupled evolution of dark matter, cosmic gas, luminous stars, and supermassive blackholes from early time to the present day, z=0. Each of the flagship runs -- TNG50, TNG100, and TNG300 -- are accompanied by lower-resolution and dark-matter only counterparts, and we discuss scientific and numerical cautions and caveats relevant when using TNG. Full volume snapshots are available at 100 redshifts; halo and subhalo catalogs at each snapshot and merger trees are also released. The data volume now directly accessible online is ~1.1 PB, including 2,000 full volume snapshots and ~110,000 high time-resolution subbox snapshots. Data access and analysis examples are available in IDL, Python, and Matlab. We describe improvements and new functionality in the web-based API, including on-demand visualization and analysis of galaxies and halos, exploratory plotting of scaling relations and other relationships between galactic and halo properties, and a new JupyterLab interface. This provides an online, browser-based, near-native data analysis platform which supports user computation with fully local access to TNG data, alleviating the need to download large simulated datasets.

Figures (6)

• Figure 1: The three IllustrisTNG simulation volumes: TNG50, TNG100, and TNG300, shown here in projected dark matter density. In each case the name denotes the box side-length in comoving Mpc. The largest, TNG300, enables the study of rare, massive objects such as galaxy clusters, and provides unparalleled statistics of the galaxy population as a whole. TNG50, with a mass resolution more than one hundred times better, provides for the detailed examination of internal, structural properties and small-scale phenomena. In the middle, TNG100 uses the same initial conditions as the original Illustris simulation, providing a useful balance of resolution and volume for studying many aspects of galaxy evolution.
• Figure 2: Spatial resolution of the three high-resolution TNG simulations at $z\sim0$. The dark regions of the distributions highlight star-forming gas inside galaxies, the corresponding median values marked by dark vertical dotted lines.
• Figure 3: Overview of the variety of physical information accessible in the different matter components of the TNG simulations. From top to bottom: dark matter density, gas density, gas velocity field, stellar mass density, gas temperature, gas-phase metallicity, shock mach number, magnetic field strength, and x-ray luminosity. Each panel shows the same $\sim 110 \times 14 \times 37$ Mpc volume of TNG100-1 at $z=0$.
• Figure 4: Illustration of the organization of particle/cell data within a snapshot for one particle type (e.g dark matter). Therein, particle order is set by a global sort of the following fields in this order: FoF group number, Subfind subhalo number, binding energy. As a result, FOF halos are contiguous, although they can span file chunks. Subfind subhalos are only contiguous within a single group, being separated between groups by an "inner fuzz" of all FOF particles not bound to any subhalo. "Outer fuzz" particles outside all halos are placed at the end of each snapshot.
• Figure 5: Four examples of exploratory plots for common scaling relations, galaxy trends, and other relationships between properties of the objects in the group catalogs, galaxies and halos, for TNG300-1 and TNG100-1 at $z=0$. Made using the web-based API functionality.