Oral Presentation
How to quantify the similarity of 2D distributions: Comparison of spatial distribution of Intracluster light and Dark Matter
Presenter: Jaewon Yoo (KASI/UST)
The study of galaxy clusters and their dynamical evolution can be greatly enhanced by comparing
their constituent components such as the dark matter, the member galaxies, the gas and the intracluster
light (ICL). However, in general, the comparison of distributions with dimension greater than 1 is a non-
trivial problem in statistics. We present a novel new methodology to quantify the similarity of two or
more 2-dimensional spatial distributions. We apply our methodology to search for a visible component
whose spatial distribution coincides with that of the dark matter, thus allowing us to produce dark
matter maps without requiring laborious weak lensing analysis. Furthermore, if such a component is
found to trace the dark matter distribution with high fidelity for more relaxed galaxy clusters, then the
similarity of the distributions may be used as a dynamical stage estimator of the cluster. We apply the
method to six galaxy clusters at different dynamical stages simulated within N-cluster Run, which is
an N-body simulation using the galaxy replacement technique. Among the various components (stellar
particles, galaxies, ICL), the ICL+ brightest cluster galaxy (BCG) component most faithfully traces
the dark matter distribution. Between the sample galaxy clusters, the relaxed clusters show stronger
similarity of the spatial distribution between the dark matter and ICL+BCG than the dynamically
young clusters.
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