Christine Corbett Moran - May 30, 2014

Globular Cluster Formation in the Virgo Cluster

Metal poor globular clusters (MPGCs) are a unique probe of the early
universe, in particular the reionization era. A popular hypothesis is
that that the observed trun- cation of MPGC formation is due to
reionization. Under this hypothesis, constraining the formation epoch
of MPGCs provides a complementary constraint on the epoch of
reionization. Moreover, as the earliest reionizing sources first
formed in galaxy clusters, systems of globular clusters in galaxy
clusters are of particular interest. We provide a self consistent dark
matter only zoom cosmological simulation to perform an analysis of the
Virgo cluster globular cluster system by identifying the present day
globu- lar cluster system with early, rare dark matter peaks. By
analyzing both the line of sight velocity dispersion and the surface
density profile of the present day distribution we are able to
constrain the redshift and mass of the dark matter peaks. Although
found to be degenerate, we quantify a dependence on the chosen line of
sight of these quantities, whose strength varies with redshift.
Coupled with star formation efficiency arguments we find a best
fitting formation mass and redshift of ~ 5 x 10^8 MSun and z ~ 9. We
predict ~ 300 intracluster MPGCs in the Virgo cluster. Our results
confirm the techniques pioneered by Moore et al. (2006) when applied
to the the Virgo cluster and extend and justify the analytic results
of Spitler et al. (2012) numerically.