Introducing the THESAN-ZOOM project: radiation-hydrodynamic simulations of high-redshift galaxies with a multi-phase interstellar medium

We introduce the THESAN-ZOOM project, a comprehensive suite of high-resolution zoom-in simulations of \(14\) high-redshift (\(z>3\)) galaxies selected from the THESAN simulation volume. This sample encompasses a diverse range of halo masses, with \(M_\mathrm{halo} \approx 10^8 - 10^{13}~\mathrm{M}_\odot\) at \(z=3\). At the highest-resolution, the simulations achieve a baryonic mass of \(142~\mathrm{M}_\odot\) and a gravitational softening length of \(17~\mathrm{cpc}\). We employ a state-of-the-art multi-phase interstellar medium (ISM) model that self-consistently includes stellar feedback, radiation fields, dust physics, and low-temperature cooling through a non-equilibrium thermochemical network. Our unique framework incorporates the impact of patchy reionization by adopting the large-scale radiation field topology from the parent THESAN simulation box rather than assuming a spatially uniform UV background. In total, THESAN-ZOOM comprises \(60\) simulations, including both fiducial runs and complementary variations designed to investigate the impact of numerical and physical parameters on galaxy properties. The fiducial simulation set reproduces a wealth of high-redshift observational data such as the stellar-to-halo-mass relation, the star-forming main sequence, the Kennicutt-Schmidt relation, and the mass-metallicity relation. While our simulations slightly overestimate the abundance of low-mass and low-luminosity galaxies they agree well with observed stellar and UV luminosity functions at the higher mass end. Moreover, the star-formation rate density closely matches the observational estimates from \(z=3-14\). These results indicate that the simulations effectively reproduce many of the essential characteristics of high-redshift galaxies, providing a realistic framework to interpret the exciting new observations from JWST.