Analysis of the Principle and Applications for the THESAN Project

The THESAN Project combines the successful IllustrisTNG galaxy simulation framework with advanced radiation transport, non-equilibrium heating and cooling, realistic ionizing sources, and a cosmic dust model. Conducted on some of the worlds most powerful supercomputers, THESAN consists of high-resolution Flagship simulation, which balances physical accuracy and box size to resolve hundreds of thousands of galaxies in a region of the universe spanning over 300 million light years. THESAN offers higher resolution than previous simulations of similar volume and employs galaxy formation simulations that match observations up to the present-day Universe. Its findings today align almost perfectly with recent observations. This study explains how THESAN accurately simulates different fields, e.g., having to consider concepts such as escape fractions and dark matter models. Moreover, to minimize errors, this simulation incorporated softening, which reduces gravitational forces on scales of 2.2ckpc. The success of this project was also due to the assistance of other simulations, including the efficient radiation hydrodynamics solver AREPO-RT, which is explained later, that can capture the interaction between ionizing photons and gas and IllustrisTNG that can predict the properties of galaxies. With THESAN simulations, humanity will be able to understand interactions both within the IGM and the future Universe.