Unveiling the hidden population of galaxies from Cosmic Dawn to Cosmic Reionization – FIRSTGAL

The FIRSTGAL project will combine ultra-deep observations from our accepted James Webb Space Telescope (JWST) large program GLIMPSE and state-of-the-art SPHINX simulations of galaxy formation to understand the feedback mechanisms that shape galaxies in the first billion years of the universe. Using a novel paired analysis between observations and simulations, the project will address the following key scientific objectives: (i) to measure the shape of the ultra-faint end of the UV luminosity function at z>6 and understand the feedback mechanisms regulating the growth of low-mass galaxies in the early Universe; (ii) to understand how stochastic star formation histories influence key physical properties of galaxies and whether it can explain the overabundance of UV-bright galaxies observed at early epochs; (iii) to determine the relative contribution of faint galaxies and AGNs and, at the same time, how cosmic variance and reionization histories affect the abundance of faint galaxies.
The FIRSTGAL project is perfectly timed to exploit the deepest observations of the distant Universe and calibrate our galaxy formation models, which have never been confronted to observations in this uncharted territory. The results and methods developed during the course of this project will be essential to the plethora of ongoing or upcoming observational facilities, such as Euclid and the ELT.