Thomas Puzia
Hertzberg Institute of Astrophysics
Extragalactic Globular Cluster Systems
The Swiss-Army Knives of Astrophysics
Monday, March 10, 2008, 4:00 p.m.
Refreshments at 3:45 p.m.
ABSTRACT
Globular Clusters are the best approximations to simple stellar
populations known to exist. Compared to the complex stellar
population mix of the diffuse (i.e. unresolved) light of their host
galaxies, the integrated light of globular clusters can be reliably
compared to population synthesis model predictions. Given that
globular clusters exist in virtually every galaxy and form during
major star formation episodes, they can be used as tracer populations
of star formation and assembly histories of their host galaxies. In
my talk, I will recapitulate evidence for the presence of multiple
globular cluster sub-populations in the Local Group. Moving on to
more massive systems, I will also present recent advance in modeling
the chemical composition distributions of globular cluster systems in
massive elliptical galaxies that appear to be consistent with the
monolithic collapse formation scenario. The comparison of model
predictions with spectroscopic observations reveals the presence of a
new, super metal-rich globular cluster population that is likely to
exist only in the most massive galaxies. Furthermore, there is strong
evidence for multiple enrichment epochs/mechanisms of the ancient
globular cluster sub-population the formation of which likely
predates the formation epoch of the vast majority of stars in
elliptical galaxies. I will discuss these results, in particular in
the context of hierarchical galaxy formation.