Large scale structure in the Universe forms in a hierarchical manner. Of the
large scale structure, galaxy clusters are the largest (~3 Mpc) and most
massive (~10^14 solar masses) virialised systems. The growth of clusters are
punctuated by periods of rapid mass gains when two cluster of roughly equal
mass merge - the most energetic event in the known Universe after the Big Bang.
It is important to understand how this merging process affects the cluster as a
whole and also the galaxies and gas within the cluster. Studying cluster mergers
is hindered by a number of problems, not the least of which is actually
determining whether a cluster has recently undergone, or is currently undergoing
a merger. A solution to this quandry may lie in the detection of "cold fronts" by the Chandra X-ray telescope. These fronts are density discontinuities in the intra-cluster medium where the gas is cooler on the denser side of the front - exactly the opposite to that expected due to a merger shock front. I have spent the last few years attempting to show these phenomena are related to merger activity so that they can be used as a reliable "merge-o-meter".
The cluster Abell 2142 - the first cold front observed with Chandra
