The Illustris Simulation: Public Data Release (1504.00362v2)

Abstract: We present the full public release of all data from the Illustris simulation project. Illustris is a suite of large volume, cosmological hydrodynamical simulations run with the moving-mesh code Arepo and including a comprehensive set of physical models critical for following the formation and evolution of galaxies across cosmic time. Each simulates a volume of (106.5 Mpc)^3 and self-consistently evolves five different types of resolution elements from a starting redshift of z=127 to the present day, z=0. These components are: dark matter particles, gas cells, passive gas tracers, stars and stellar wind particles, and supermassive black holes. This data release includes the snapshots at all 136 available redshifts, halo and subhalo catalogs at each snapshot, and two distinct merger trees. Six primary realizations of the Illustris volume are released, including the flagship Illustris-1 run. These include three resolution levels with the fiducial "full" baryonic physics model, and a dark matter only analog for each. In addition, we provide four distinct, high time resolution, smaller volume "subboxes". The total data volume is ~265 TB, including ~800 full volume snapshots and ~30,000 subbox snapshots. We describe the released data products as well as tools we have developed for their analysis. All data may be directly downloaded in its native HDF5 format. Additionally, we release a comprehensive, web-based API which allows programmatic access to search and data processing tasks. In both cases we provide example scripts and a getting-started guide in several languages: currently, IDL, Python, and Matlab. This paper addresses scientific issues relevant for the interpretation of the simulations, serves as a pointer to published and on-line documentation of the project, describes planned future additional data releases, and discusses technical aspects of the release.

• The paper introduces a public release of high-resolution cosmological simulations detailing galaxy evolution and cosmic structure formation.
• It employs moving-mesh hydrodynamics with full baryonic physics across 136 redshift snapshots to support diverse astrophysical studies.
• The dataset provides comprehensive group catalogs, merger trees, and API tools, enabling detailed exploration of star formation and galaxy mergers.

The Illustris Simulation: Data Release and Scientific Insights

The paper "The Illustris Simulation: Public Data Release" outlines the publicly available dataset from the Illustris Project, a series of cosmological hydrodynamical simulations. These simulations are renowned for their capacity to model the universe’s structure formation and galaxy evolution over cosmic time, utilizing the moving-mesh code Arepo. The release of this dataset provides a comprehensive set of resources for the astrophysical community, encouraging further investigations into various astronomical phenomena.

Overview of Illustris Simulations

The Illustris Project comprises simulations of a (106.5 Mpc)$^3$ cosmological volume, modelling dark matter particles, gas cells, passive gas tracers, stars, stellar wind particles, and supermassive black holes. The simulations start from a high redshift of $z=127$ and evolve to the present epoch. Three resolution levels are available, with each run featuring full baryonic physics as well as dark matter-only scenarios. The flagship run, Illustris-1, achieves high resolution, allowing for detailed investigation of astrophysical processes down to kpc scales.

Data Products and Accessibility

The datasets released encompass a wide array of products:

1. Snapshots: Covering 136 redshifts, these provide detailed particle and cell data, enabling the paper of the universe’s structure across different epochs.
2. Group Catalogs: Utilizing friends-of-friends (FoF) and Subfind algorithms, these catalogs identify and categorize substructures within the simulation, essential for analyzing galaxy and halo properties.
3. Merger Trees: Two distinct tree structures (SubLink and LHaloTree) map the evolutionary histories of subhalos, supporting studies on galaxy mergers and growth.
4. Supplementary Catalogs: Additional products focus on $z=0$ galaxy properties, including synthetic images and morphological measurements.

All data are accessible via direct download or through a versatile web API, offering searches, data extraction, and visualization tasks, supporting a multitude of astrophysical research inquiries.

Scientific Implications and Limitations

The release of the Illustris data yields numerous opportunities for theoretical and observational astrophysics. The simulation outcomes have already been pivotal in exploring galaxy star formation histories, morphological characterizations, and the impact of feedback processes on baryonic structures. Nevertheless, the paper notes caution on specific model limitations and discrepancies with observations, emphasizing areas where feedback implementations may overestimate or underestimate effects, particularly in predicting star formation rates and halo gas content.

Future Developments

Planned expansions to the Illustris dataset include enhanced datasets such as high-time-resolution subboxes and additional modeling outputs like strong lensing mocks and evolving stellar mocks across high redshifts. The continued enrichment of this dataset will inevitably contribute to resolving existing questions and uncovering new aspects of cosmic structure formation.

The paper's description of the Illustris data release provides an essential resource, empowering the community to explore the intricate processes governing cosmic evolution. Collaboration and contributions from the broader research community are encouraged, promising a participative approach to tackling outstanding astrophysical puzzles using the Illustris simulation data. This openness fosters advancements in both simulation techniques and the scientific questions they address.