Are the Effects of Structure Formation Seen in the Central Metallicity
  of Galaxy Clusters?
  A sample of 46 nearby clusters observed with Chandra is analyzed to produce
radial density, temperature, entropy and metallicity profiles, as well as other
morphological measurements. The entropy profiles are computed to larger radial
extents than in previous Chandra cluster sample analyses. We find that the iron
mass fraction measured in the inner 0.15 R500 shows a larger dispersion across
the sample of low-mass clusters, than it does for the sample of high-mass
clusters. We interpret this finding as the result of the mixing of more haloes
in large clusters than in small clusters, which leads to an averaging of the
metal content in the large clusters, and thus less dispersion of metallicity
for high-mass clusters. This interpretation lends support to the idea that the
low-entropy, metal-rich gas of merging haloes reaches clusters' centers, which
explains observations of Core-Collapse Supernova products metallicity peaks,
and which is seen in hydrodynamical simulations. The gas in these merging
haloes would have to reach the centers of clusters without mixing in the outer
regions, in order to support our interpretation. On the other hand, metallicity
dispersion does not change with mass in the outer regions of clusters,
suggesting that most of the outer metals come from a source with a more uniform
metallicity level, such as during pre-enrichment. We also measure a correlation
between the metal content in low-mass clusters and the degree to which their
Intra-Cluster Medium (ICM) is morphologically disturbed, as measured by
centroid shift. This suggests an alternative interpretation of the large width
of the metallicity distribution in low-mass clusters, whereby a metallicity
boost in the center of low-mass clusters is induced as a transitional state,
during mergers.
