17/05/2006 – 14h – Auditório Principal, Bloco G – IAG/USP

Ignacio de la Rosa

IAG/USP e Instituto de Astrofísica de Canarias/Espanha

Título/Title: Porque estão se apagando as galáxias?

Resumo/Abstract:

Studies of the global star formation rate show a decline of a factor 3-10 since the peak of star formation at z = 1-2. Possible explanations can be summarized into two alternative hypotheses: (1) The down-turn is caused by galaxies running out of a supply of material for star formation, or (2) it is driven by the growth of the mass structure of the Universe and the changing environments of galaxies. Although, several mechanisms have been proposed to quench the star formation in galaxies, they are only viable in the environment of the dense clusters. A more global mechanism is needed, because clusters are rare objects, containing less than 10% of the cosmic galaxy population. Recent hydrodynamical simulations point to the merger of galaxies as such a mechanism, because it triggers an AGN feedback that quenches the star formation of the galaxy on a short timescale.

In a recent study of stellar populations in galaxies, we have searched for traces of quenched star formation in one of the most favorable environments for mergers, the Hickson Compac Groups, which combine high galaxy densities with low velocities. The results of this study will be discussed and extended to the interpretation of the global case.

<= Volta para lista de seminários/Back to seminar schedule