Qualitative illustration of the various physical quantities predicted by the THESAN-ZOOM simulations. The central image shows the large-scale (2 cMpc) gas density distribution around a zoom-in galaxy, with the white circle denoting its virial radius. The smaller surrounding images showcase a smaller region of 100 ckpc around the central galaxy, and the circles indicate the half-mass radius of stars. Clockwise from bottom-left, the image shows the neutral hydrogen fraction, molecular hydrogen fraction, gas phase metallicity, dust-to-gas-ratio (DGR), dust temperature distribution, gas temperature distribution, the LyC photon density, and a mock JWST image generated from the F277W, F356W, F444W bands.
Illustration of the zoom-in technique used in the the THESAN-ZOOM simulations. The background shows the projected gas density, with filaments clearly visible, along with the transition between the low- and high-resolution regions. The two inset panels focus on the temperature and neutral hydrogen density of the central galaxy, demonstrating the high level of fidelity seen in zooms.
Treatment of the boundary conditions for the radiation field at the edge of the high-resolution region (marked by the white contour) in the THESAN-ZOOM simulations. The color-coded map shows the neutral hydrogen photoionization rate, and the arrows indicate the photon flux. Our unique framework incorporates the impact of patchy reionization by adopting the large-scale radiation field topology from the parent THESAN simulation box. In this example, the high-intensity external ionizing source present in the parent simulation, shown on the left of the zoom-in region, reionizes the targeted galaxy outside-in.
