The Distribution of Baryons in Galaxy Clusters and Groups
Anthony Gonzalez (University of Florida)
If galaxy clusters are indeed fair samples of the universe, then a basic
expectation is that the baryon fraction in clusters and groups should
reflect the universal value. Observed shortfalls have therefore led to
proposals of missing baryons in a warm gas component, as well as other
more controversial interpretations. I will present the results of a program
to understand the distribution of baryons in nearby galaxy clusters and
groups, as well as the properties of their central galaxies. A main focus
of this work is to quantify the total stellar baryon fraction, including
stars in both galaxies and the intracluster light, and combine these data
with published measurements of the hot baryon fraction in the intracluster
medium (ICM). We find that the total baryon fraction is independent of cluster
mass, with no compelling evidence for missing baryons. I will also present
related results from this program pertaining to cluster galaxy evolution,
galaxy structure, and chemical enrichment of the ICM.
