Description
Since the launch of JWST, the advent of high-redshift spectroscopy has supercharged the discovery of strange objects with anomalous UV brightnesses, unexpected carbon and nitrogen abundance patterns, and ionizing spectra from extremely hot stellar populations, all wrapped up in physical sizes which point to incredible stellar and gas densities. With modern galaxy evolution simulations striving to explore this frontier, it is becoming abundantly clear that doing so accurately requires precise considerations of the formation, evolution and feedback (both mechanical and radiative) from a variety of typical and extreme stellar populations. However, all of this must be done in the context of a well-resolved, multi-phase interstellar medium (ISM) surrounded by the turbulent environment of a high-redshift halo. To this end, I will present first results from the MEGATRON suite of high-resolution cosmological radiation hydrodynamical zoom simulations which for the first time feature non-equilibrium chemistry and heating/cooling processes coupled to on-the-fly radiative transfer: tracing the births and deaths of population III and II stars in the early universe.
Specifically, I will be discussing how the ISM phase structures of high-redshift galaxies evolve as they transition from the population III to population II regime. Furthermore, I will explore the impact that this evolution has on the direct observable properties of these objects, such as their line strengths, UV diagnostic diagrams, UV continuum slopes, and ionizing efficiencies. All of this will be contextualized with present-day JWST observational data, focusing on the few population III candidates that have already been presented in the literature.
