RT info:eu-repo/semantics/doctoralThesis
T1 Galaxies with multiple bars : constraints on their formation scenarios
A1 Lorenzo-Cáceres Rodríguez, Adriana de
K1 Galaxias
K1 Espectroscopia
K1 Astronomía y Astrofísica
AB Much of current astrophysical research is aimed at addressing one key issue:how galaxies form and evolve. We still do not fully understand the evolutionaryprocesses driving the lifetimes of the zoo of galaxies which populate theUniverse. Galaxies may be isolated, or in groups or clusters; they may appearas pure ellipsoids or discs or include a variety of structures; they may be formingstars violently or passing quietly through their lives; and the many other propertiesthat we are progressively discovering. Each piece we add to the puzzlepile complicates the picture a bit more. This thesis is aimed at fixing one ofthese pieces, a specific one related to the very interesting, but so far not wellcharacterised, double-barred galaxies.Barred galaxies are rather common structures in the Universe and, moreimportantly, they are key elements for secular evolution theories. In fact, barscan transport gas to the central regions of galaxies and trigger the formationof bulges and other new structures. Double bars go a step farther: they allowthe material to reach the very central regions where the gas driven inwards bya single bar cannot get to. Therefore, nested bar systems are considered a veryefficient way to bring about the internal secular evolution of galaxies and evento feed active galactic nuclei. This hypothesis has, however, some detractors,as it is very promising from a theoretical point of view but there is not muchobservational evidence that it is valid.In this thesis we have carefully observed and studied a sample of five doublebarredgalaxies using the state-of-the-art techniques for the analysis of theirkinematics and stellar populations. This has led to original work not previouslyperformed, so each result is relevant and provides clues to the natureof these objects. We are pleased to present the discovery of the σ-hollows, theonly known kinematical signature of the presence of stellar inner bars. Moreover,we disentangle the complex structural composition of the galaxies of oursample, dealing with different formation scenarios and rejecting those which donot account for the observational properties derived here. We find out that one out of the five galaxies is probably hosting a disc-like bulge, whereas theother four present a classical bulge in their centres. Finally, we ascertain thatinner bars tend to be younger and more metal-rich than the outer structures.Nevertheless, the characteristic stellar populations for the bulge and the innerbar are indistinguishable and there is no evidence of star-forming structures inthe central regions of these galaxies, so we have to conclude that these five innerbars are not playing a major role in the secular evolution of their host galaxies
PB Universidad de La Laguna, Servicio de Publicaciones
SN 978-84-15939-04-7
YR 2014
FD 2014
LK http://riull.ull.es/xmlui/handle/915/53
UL http://riull.ull.es/xmlui/handle/915/53
LA en
DS Repositorio institucional de la Universidad de La Laguna
RD 26-abr-2024