Stellar populations in galaxy clusters
Galaxy clusters are the cosmic environments where galaxy evolution progress faster. Exploring the stellar population properties of the galaxies in those structures at different redshifts allows to probe the early mechanisms of galaxy formation and how the assembly of the different pieces of the cluster transform the properties of the infalling galaxies. Our group is conducting, using ultradeep spectra from the Gemini and VLT telescopes, an in-depth study of the stellar population properties of the galaxies in rich clusters between 0 < z < 1. These studies are complemented with deep HST imaging.
Evolution of massive galaxies
Once understood as the paradigm of passively evolving objects, the discovery that massive galaxies experienced an enormous structural evolution in the last ten billion years has opened an active line of research which our group is leading in many different fronts. The most significant pending question in this field is the following: which mechanism has made galaxies to grow largely in size without altering their stellar populations properties dramatically. The most viable explanation is that massive galaxies have undergone a significant number of minor mergers which have deposited most of their material in the outer regions of the massive galaxies. This scenario, although appealing, is still far from be observationally proved since the number of satellite galaxies surrounding the massive objects appears insufficient at all redshifts. The presence also of a population of nearby massive compact galaxies with mixture stellar properties is another piece of the puzzle that still does not nicely fit within a comprehensive scheme.
Spectro-photometry of SDSS galaxies
High quality spectra of the nearby galaxies contain a plethora of information about the evolutionary process galaxies have undergone during their life. To extract such information and confront it directly with the high-z universe, our group has developed several tools to extract the star formation histories from the nearby objects.
Numerical simulations of massive galaxies
Numerical simulations are a powerful tool to test hypotheses about the processes that drive galaxy formation and evolution. Numerical simulations allow us to choose the properties of the objects under study, to isolate specific physical mechanisms and to control the initial conditions of the dynamics. We use a numerical code named GADGET-2 running in supercomputers at which we have granted access via the Red Española de Supercomputación. One of the lines of research in our group is the study of the size evolution of massive galaxies over cosmological timescales. We test the hypothesis that massive galaxies grow in size via mergers with smaller galaxies. To that end, we have performed a set of cosmologically motivated high-resolution numerical simulations, to follow the structural changes that a massive elliptical galaxy experiences since redshift ~2.5 to the present. Comparing our findings with observed galaxies we can confirming the hypothesis and also make predictions that guide future observational tests.