Multi-wavelength Investigations of Galaxy-Hot Plasma Interactions in Clusters of Galaxies

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We have continued and extended the research topic, the cosmological infall of galaxies into the centre of galaxy clusters (originally proposed by Makishima et al. 2001), by carrying out a much more comprehensive study on the three main mass components i.e., galaxies, hot ICM, and dark matter, in the galaxy clusters.In collaborating with optical astronomers (Prof. Han and Dr. Wen) in National Observatory of China, we compiled a sample of 340 galaxy clusters in redshift range of 0.1-0.5. The size of the sample is 10 times as the one used in Gu et al. (2013). In this work I played a central role in analyzing both X-ray and optical data. We have detected, following Gu et al. (2013), a significant evolution on a cosmological timescale: galaxies have been centrally concentrated with time relative to the ICM and dark matter, while the ICM has been expanding compared to dark matter even they keep radiating. This evolution is not solely driven by gravitational effects such as dynamical friction between galaxies and cluster matters. The result will be submitted soon to the Astrophysical Journal.References: Makishima, K. et al. 2001, PASJ, 53, 401; Gu, L. et al. 2013, ApJ, 767, 157; Gu, L. et al. 2014, in prep.