Kinematics and stellar populations of galaxies in the local universe

• Autor(a) principal: Carlos Eduardo Barbosa
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://doi.org/10.11606/T.14.2018.tde-22042018-235533

Galaxies are the major building blocks of the universe, but we are still learning about fundamental aspects of their formation. In particular, we would like to understand how galaxies acquire their stars, and where and when these stars were born. In this thesis, we investigate these questions by the study of the dynamical and chemical abundances of galaxies in the local universe. Extending previous works in the field, we have developed a Bayesian framework to obtain luminosity-weighted ages, metallicities and alpha-element abundances. In our initial study, we have surveyed six galaxy groups to understand how this particular environment may be related to morphological transformations. We have obtained a sample of 59 group members with a wide range of dynamical masses, which have been used to demonstrate that the mass-metallicity relation extends to low-mass galaxies. We then proceeded to the study of NGC 3311, a cD galaxy at the center of the Hydra I cluster. We have confirmed previous observations of the velocity dispersion profile of the system, which indicates the presence of a large photometric substructure which illustrates the ongoing accretion of the diffuse stellar halo. We performed a study of the stellar populations of the system, which indicated that stars in the diffuse stellar halo have been accreted from past merger events of large elliptical galaxies, whereas the central region of the galaxy is most probably the remnant of a rapid dissipative collapse. Moreover, the metallicity of the stars in the photometric substructure suggest an ongoing disruption of dwarf galaxies possibly related to the presence of an infalling group. These results are consistent with the two-phase model for the mass assembly of galaxies, in which massive ellipticals are formed by dissipative processes at high-redshifts, but continue to build-up their halos by the continuous accretion of satellite systems.