Galactic properties that favour star cluster formation: a statistical view
Abstract
The presence or absence of star clusters in galaxies, and the properties of
star cluster populations compared to their host galaxy properties, are
important observables for validating models of cluster formation, galaxy
formation, and galaxy assembly. In this work, we apply a Bayesian approach to
fit two models to data from surveys of young clusters in star forming galaxies.
The first model is a logistic regression, which allows us to include galaxies
which do not have any young clusters. The second model is a hurdle model, which
includes galaxies with zero clusters and also incorporates information about
the total mass in the cluster system. We investigate two predictors (star
formation rate and total stellar mass in the galaxy) and look at clusters
younger than 10 or 100 Myr. We find that in all cases, star formation rate is
the better predictor for both the probability of hosting clusters and the total
mass in the cluster system. We compare our results to similar models for old
globular clusters, and conclude that star cluster formation was more abundant
and more efficient at higher redshifts, likely because of the high gas content
of galaxies at that time.