Gas flows in and out of galaxies and it is converted into stars, which subsequently release their nucleosynthesis products, ‘metals’, into the inter-stellar medium (ISM). These are then mixed with metals already present or accreted and get reincorporated into the next stellar generations. This baryonic cycle and metal enrichment is influenced both by internal properties regulated by the mass scale of galaxies and by external mechanisms regulated by the evolving environment in which galaxies reside. Clues to the relative role of these different drivers can come from disclosing the archaeological information of galaxies star formation and assembly history from their spectra, and relating it to mass and environmental metrics. Analysis of SDSS spectroscopic data shows that the physical properties of stellar populations in galaxies (age, metallicity, element abundance ratios) correlate with galaxy stellar mass. At a given stellar mass, they further depend on whether a galaxy sits at the center of its dark matter halo (central galaxy) or has been accreted and orbit as a satellite galaxy, and on the mass of the host dark matter halo. These trends reveal the action of gas-stripping processing in suppressing star formation in lower-mass satellites, and earlier more efficient star formation in massive galaxies residing in cosmic density peaks.
This thesis aims at exploiting the most recent stellar population determination for SDSS galaxies, accounting of new population synthesis modeling and corrections for observational biases and volume completeness, to characterize in detail how the scaling relations and the demographics of galaxies in physical parameter space change as a function of halo mass and for centrals versus satellites. Scaling relations of stellar population properties as a function of mass for the general galaxy population show a bimodal distribution transitioning from a young, metal-poor regime to an old, metal-rich regime around a characteristic stellar mass. While this bimodality largely corresponds to passive and star-forming galaxies, a population of young passive galaxies emerges.
This thesis will specifically address how the characteristic scale of transition changes with environment and whether the population of low-mass young passive galaxies originate from recent environmental quenching. This work paves the way for the analysis of deep spectroscopic surveys at intermediate redshifts with both accurate stellar population information and environmental characterization that will start soon, such as WEAVE-StePS and 4MOST-StePS/WAVES.