Una nuova visione sulla relazione tra massa e metallicità stellare in galassie quiescenti: effetto delle abbondanze chimiche, della storia di formazione stellare ed dell'evoluzione in redshift

The star formation history of galaxies can be reconstructed from the properties of their stellar populations, like their age and metallicity. Observations of nearby quiescent, early-type galaxies (ETGs) picture a downsizing scenario, where the stellar content of the most massive ones formed early on, in a short and intense stellar burst, while that in lower-mass ETGs formed later on and over longer timescales. While the downsizing reflects a statistical probability of their formation, ETGs actually assembled their mass following different paths. The average trends, upon which current galaxy formation models are built, can then be limiting in describing the overall formation history of ETGs. Further, nearby galaxies are affected by cosmic evolution effects, like mergers and gas accretion, contaminating their observed properties and blurring the actual trends. To mitigate this effect, in this work, I study the stellar population properties of a large sample of quiescent ETGs at redshift 0.6 ≤ z ≤ 1. In particular, I propose a different outlook on the mass-metallicity relation by probing the existence of a flat upper limit to metallicity, and a lower limit that depends on the mass, and I study the effect of the SFH and redshift evolution. Finally, I present the spectral analysis of a massive quiescent galaxy observed with JWST at z ∼ 2, allowing, for the first time, to simulatenously measure the optical and NIR galaxy spectrum outside the local Universe.