Poblaciones estelares, formación y evolución de galaxias quiescentes a desplazamientos al rojo intermedios a partir de cartografiados multifiltro

Resumen

This Ph. D. thesis aims at improving our understanding of the evolution of quiescent galaxies since z=1, with the ultimate goal of providing a general picture for the formation and evolution of these objects along the history of the Universe. Making use of data from the ALHAMBRA survey and the SED-fitting code MUFFIT, developed as part of this work, this thesis is novel at facing for the first time an extensive, observational study that comprises the time evolution of the number density of quiescent galaxies, as well as their masses, stellar populations (ages, metallicities and extinctions) and sizes, to ultimately build up a phenomenological evolutionary model based on the merger, frosting and progenitor bias scenarios that tries to reconcile the observed trends in the above parameters. The stellar population parameters of quiescent galaxies are obtained by the novel and generic code MUFFIT, which was specifically designed to analyse the stellar content of galaxies with available multi-filter data. MUFFIT performs an error-weighted chi2-test to provide the most likely range of stellar population parameters (ages, metallicities, extinctions, redshifts, stellar masses, and uncertainties), after removing from the analysis those bands that are significantly affected by emission lines. For the construction of a reliable sample of quiescent galaxies, we take advantage of the extinctions retrieved via MUFFIT to built a dust-corrected UVJ- diagram of intrinsic colours clean of dusty star-forming galaxies. Our reference sample is complete in stellar mass and composed of 8547 galaxies from ALHAMBRA up to z=1.1 (photo-z accuracy of 0.6%). Through the stellar population parameters of quiescent galaxies retrieved by MUFFIT using ALHAMBRA data, we build, for the first time, the analytic probability distribution functions of mass-weighted age, metallicity, and extinction for accurately studying the evolution of the quiescent galaxy population. Quiescent galaxies show older ages at larger cosmic times, solar and super-solar metallicities predominantly, and low extinction values . The more massive the quiescent galaxy is, the older and more metal-rich it is. We find that the evolution of quiescent galaxies differs respect a passive evolution, and that the median mass-weighted metallicity exhibits a decrease of 0.1-0.2 dex since z~0.6-1.0. All the qualitative results were confirmed using two different sets of SSP models and alternative assumptions for the star formation history. A phenomenological model is developed for discerning the impact of mergers, frosting (on- going star formation), and the progenitor bias (new quenched galaxies) on the evolution of massive quiescent galaxies from z=1 to z=0.2. Our results point out that frosting is an indispensable mechanism for explaining the evolution of quiescent galaxies, that along with mergers and the progenitor bias greatly reconcile, for the first time, the evolution with redshift of the observed ages, metallicities and number densities of massive quiescent galaxies. By hundreds of galaxies with stellar population parameters and sizes in ALHAMBRA, we discern the correlations between the stellar content of quiescent galaxies and their sizes. The more compact the quiescent galaxy, the older, more rich in metals, lower extinctions and lower SFR/sSFR values exhibits. From these results: the formation and evolution of the stellar populations of quiescent galaxies relate to the stellar mass, but also with the stellar mass density of the galaxy; and some scenarios (e.g. "puffing-up" scenario) for explaining the growth in size of quiescent galaxies are discarded. In addition, through 379 massive spheroid-like galaxies from the NIR Palomar/DEEP2 survey, we found that their companions are not located preferentially around the more compact or extensive massive spheroid-like galaxies.