Matteucci Maria Francesca
Dipartimento di Fisica, Università degli studi di Trieste (Trieste, Italie)
chemical evolution. In particular, I will present detailed models for both the Milky Way and high-redshift galaxies, which trace the evolution of gas and its chemical composition as driven by star formation histories, stellar nucleosynthesis, and gas inflows and outflows. For the Milky Way, I will discuss the observed bimodality in the [a/Fe] ratio, where a-elements include O, Mg, S, Si, and Ca, between the thick and thin disks, and examine possible interpretations. If confirmed, this bimodality may reflect a temporary quenching of star formation between the formation of the two components, a late gas accretion event, or the effects of stellar radial migration.
I will then address recent observations from JWST, which reveal supersolar N/O
ratios in galaxies at very high redshift (e.g. z ˜ 10.6), despite their overall low metallicity. This combination poses a challenge for standard chemical evolution models. I will explore possible explanations, focusing in particular on scenarios involving intense star formation combined with differential galactic winds, where certain elements are preferentially removed from galaxies. Finally, I will present predictions for the evolution of the cosmic metallicity, the metal content per unit comoving volume of the Universe, showing that it can reach values of ~0.1–0.3 Z? within the first 200 Myr across a wide range of galaxy formation scenarios, in agreement with recent JWST results.
Amphithéâtre Henri Mineur, Institut d'Astrophysique de Paris