illustris

Illustris is a suite of cosmological hydrodynamical simulations of galaxy formation conducted within a representative volume of the universe. The project represents an international collaboration aimed at modeling the formation and evolution of galaxies from early times to the present, incorporating dark matter, gas dynamics, and feedback processes that shape galaxy properties.

The simulations were run with the AREPO moving-mesh code, combining gravity and hydrodynamics with subgrid models for radiative cooling, star formation, chemical enrichment, and feedback from stars and active galactic nuclei. The volume is designed to capture large-scale structure while resolving individual halos and galaxies, enabling comparisons with a range of observational data.

Outputs from Illustris include catalogs of dark matter halos and galaxies, merger trees, and synthetic observables such as stellar masses, star formation rates, and galaxy colors. The simulations were used to test and interpret observational statistics, including the galaxy stellar mass function, the star formation main sequence, and the distribution of galaxies within halos, while acknowledging areas where the models faced challenges.

The Illustris project also released its data to the scientific community via a public portal, providing access to halo catalogs, merger trees, and galaxy properties for researchers worldwide. The work has influenced subsequent simulations, most notably IllustrisTNG (The Next Generation), which extends the project with updated physics, larger volumes, and refinements in numerical methods.

In common usage, the name Illustris often refers to the original simulation set, but it forms the foundation of an ongoing program that has contributed significantly to the study of cosmology and galaxy formation.