The IllustrisTNG simulations: public data release

Abstract

We present the full public release of all data from the TNG100 and TNG300 simulations of the Illus-trisTNG 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 selfconsistently 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 halo/subhalo catalogs, merger trees, lower-resolution and darkmatter only counterparts, all available with 100 snapshots. We discuss scientific and numerical cautions and caveats relevant when using TNG.The data volume now directly accessible online is ∼750 TB, including 1200 full volume snapshots and ∼80,000 high time-resolution subbox snapshots. This will increase to ∼1.1 PB with the future release of TNG50. Data access and analysis examples are available in IDL, Python, and Matlab. We describe improvements and new functionality in the webbased 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 Jupyter-Lab interface. This provides an online, browserbased, near-native data analysis platform enabling user computation with local access to TNG data, alleviating the need to download large datasets.

Interacting galaxies in the IllustrisTNG simulations - I: Triggered star formation in a cosmological context

“…Our study is primarily focused on the cosmological hydrodynamical simulations from the IllustrisTNG 1 suite. Illus-trisTNG is the successor to the Illustris simulations (see below), with numerous updates that are described in the public data release (Nelson et al 2019). Weinberger et al (2018) and Pillepich et al (2018a) provide a complete description of the physical models.…”

“…Subhalo catalogues are available at 100 redshifts, including 50 snapshots at z < 1. Following Nelson et al (2019), we exclude SUBFIND subhalos for which the SubhaloFlag parameter has been set to 0, as they are known to be sub-galactic clumps and are not considered to be bona fide galaxies. Properties of these simulations (and others described below) are summarised in Table 1.…”

“…Given that there is substantial overlap between galaxies at these small relative separations, we attribute this more rapid decline as being caused by numerical stripping. In order to identify the regime in which numerical stripping is prevalent, we carried out an extensive visual inspection of synthetic stellar images of galaxies from both TNG100-1 (Nelson et al 2019) and Illustris-1 (Torrey et al 2015). This inspection focussed on systems with r sep < 3, which corresponds to typical 3D separations of r 30 kpc for TNG100-1 and r 60 kpc for Illustris-1.…”

“…Fortunately, the availability of increasingly realistic cosmological hydrodynamical simulations provides a way forward on many of these issues. Simulations such as Illustris (Vogelsberger et al 2014a), Horizon-AGN (Dubois et al 2014), EAGLE (Schaye et al 2015), MassiveBlack-II (Khandai et al 2015), SIMBA and Il-lustrisTNG (Nelson et al 2019) yield thousands of massive galaxies within volumes spanning at least (100 Mpc) 3 , with properties that are well matched to galaxy populations at low redshift. Galaxy interactions and mergers arise naturally within these simulations, with a full distribution of orbits, spin-orbit orientations, environments and galaxy properties.…”

Interacting galaxies in the IllustrisTNG simulations – II: star formation in the post-merger stage

“…Using numerical simulations mitigates the unconstrained merger timescales in observational studies, while the large simulation box provides a diverse and representative galaxy sample therefore alleviating a major challenge for idealised and cosmological zoom-in simulations. We identify galaxy mergers in the IllustrisTNG simulation suite (Marinacci et al 2018;Naiman et al 2018;Nelson et al 2018;Pillepich et al 2018b;Springel et al 2018;Nelson et al 2019a) and then analyse our post-merger galaxy sample by implementing a methodology akin to observations. By comparing the post-merger star formation rates to controls which have not undergone a merger, we are able to isolate the effects of the merger on star formation rates (e.g., Patton et al 2020).…”