Thesis

The nature and formation history of pseudo-bulges in galaxies

• Call:

  IDPASC Portugal - PHD Programme 2014

• Academic Year:

  2014 /2015

• Domain:

  Astrophysics

• Supervisor:

  Polychronis Papaderos

• Co-Supervisor:

  Jean Michel Gomes

• Institution:

  Universidade do Porto

• Host Institution:

  Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP

• Abstract:

  The featureless appearance of bulges in Hubble-type galaxies has for decades sustained the view that these high-surface brightness spheroidal components are largely ``simple'' in terms of their assembly history, formed on a short timescale early on, and having experienced little evolution over the past several Gyr. However, our early understanding of bulges as essentially scaled ellipticals has undergone a substantial revision over the last years. It is now recognized that central luminosity components that closely resemble classical bulges can also form over much longer timescales through disk instabilities and ensuing star forming activity at the centers of galaxies. The nature and formation history of these “pseudo-bulges” is enigmatic and of considerable relevance to our understanding of the structural and spectrophotometric evolution of galaxies in general. This PhD project aims at a spatially resolved investigation of the star formation- and chemical enrichment history of pseudo-bulges. A unique aspect of its methodology is the combined application of surface photometry and spectral population synthesis to a large sample of galaxies from the Calar Alto Legacy Integral Field spectroscopy Area survey (http://califa.caha.es) with the goal of conclusively addressing the star formation history (SFH) and the chemical abundance patterns of pseudo-bulges. One of the central questions to be investigated is whether pseudo-bulges form in a quasi-continuous manner over several Gyrs of galactic evolution and their SFH can be parametrized through a simple functional form involving integral or structural properties of their host galaxy (e.g., total stellar mass; central surface brightness and exponential scale length of the underlying disk). Additionally, this project will include a comparative study of pseudo-bulges and classical bulges with the goal of the identification of new empirical discriminators between them and yield robust observational constraints to theoretical models of pseudo-bulge formation and evolution.