Merger of Clusters of Galaxies

According to the hierarchical clustering scenario, it is believed that clusters of galaxies (CGs) are formed through subcluster mergers and/or absorption of smaller galaxy groups. In such CGs, complex electron temperature distribution and characteristic X-ray surface brightnes distribution (substructures, elongation) are expected in intracluster medium (ICM). In recent years, indeed, rather complex electron temperature structures are revealed in merging CG through X-ray observations.

We introduce some results of N-body and hydrodynamical simulations for cluster mergers by one of our group (MT). To get more detailed information, please see Takizawa 1999 (ApJ vol.520 p.514), and Takizawa 2000 (ApJ vol.532 p.183)

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Time evolution of various physical quantities during 1:4 cluster merger: (a)the total X-ray luminosity, (b)the emissivity-weighted mean electron temperature, (c)the square root of velocity dispersion parallel to the collision axis, (d) the specific energy ratio of dark matter and ICM.

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Snapshots of X-ray surface brightness (contours) overlaid with emissivity-weighted electron temperature (colors) distribution seen from the direction perpendicular to the collision axis during 1:4 merger.

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Evolution of the ICM velocity field during 1:4 merger seen from the direction perpendicular to the collision axis.

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