Unravelling the complexity of the reionization history though simulations and multi-wavelength observations (RECAP)

Research Project, 2025 – 2030

The epoch of Reionization marks the last major transition of the Universe: approximately 400.000 year after the Big bang, the neutral intergalactic medium, mainly composed of hydrogen atoms, started to be ionized by high-energy radiation from the first cosmic sources, stars, galaxies. The onset, timeline and topology of the Reionization process are all tightly linked to the nature of the sources of ionizing radiation: by identifying and studying them we can gain fundamental insights into what shaped the evolution of the universe, from the smooth matter distribution of early times, as revealed by the CMB, to the wealth of structures, like galaxies and clusters of galaxies that formed at later epochs. Our project will exploit the critical synergies in expertise of the 4 PIs and their teams, from the modeling of the intergalactic medium ionization and metal enrichment, to detailed observations of the ionizing sources, to shed light on their properties, their environment and the complex energy and baryon exchange between them and the intergalactic medium. We will exploit new extensive datasets coming from state-of-the-art facilities, such as the recently launched JWST, present and future VLT instrumentation and ALMA. To support and drive the interpretation of these new observations, we will develop a novel algorithm to model a self-consistent non-equilibrium 3D multi-frequency radiative transfer through H, He, metals and dust and produce both large scale and zoomed-in simulations that can be readily compared to real data. The proposed research aims at making fundamental steps to decode the mysteries of Cosmic Dawn and solve some of the puzzles in our current theories of early galaxy formation