The origin of unusual chemical abundances from the JWST

To understand the formation and evolution of the Universe, it is crucial to understand how and when the first stars formed. The latest observational data reveal unprecedented information about the chem- ical enrichment of the early Universe, which seems to behave differently from the local Universe. The first stars, being very massive, enrich their metal-poor environment in an uncertain way. In order to predict the abundances of the first galaxies, we include nucleosynthesis yields from Population III stars up to 300M⊙, including faint supernovae, Wolf-Rayet (WR) stars and Pair-Instability Supernovae (PISN) into our state- of-the-art hydrodynamical cosmological simulations. Our code (based on Gadget-3) also includes the latest nucleosynthesis yields from population II stars (from Kobayashi et al. 2020) for all stellar mass ranges. We predict the chemical abundance evolution of galaxies for different elements from the early Universe to the local Universe. We first test the modelling of stellar feedback by comparing the observed evolution of mass–metallicity relations (MZR) and metallicity gradients of the interstellar medium. We then com- pare our model including Population III stars with observational data from the James Web Space Telescope (JWST). For elemental abundances, we find that the N/O abundance gives a systematically higher value, comparable to the observational data of very high-redshift galaxies such as GN-z11.