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arXiv · 1410.2893

MC^2: Galaxy Imaging and Redshift Analysis of the Merging Cluster CIZA J2242.8+5301

William A. Dawson·M. James Jee·Andra Stroe·Y. Karen Ng·Nathan Golovich·David Wittman·David Sobral·Marcus Bruggen·H. J. A. Rottgering·R. J. van Weeren
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Abstract

X-ray and radio observations of CIZA J2242.8+5301 suggest that it is a major cluster merger. Despite being well studied in the X-ray, and radio, little has been presented on the cluster structure and dynamics inferred from its galaxy population. We carried out a deep (i<25) broad band imaging survey of the system with Subaru SuprimeCam (g & i bands) and the Canada France Hawaii Telescope (r band) as well as a comprehensive spectroscopic survey of the cluster area (505 redshifts) using Keck DEIMOS. We use this data to perform a comprehensive galaxy/redshift analysis of the system, which is the first step to a proper understanding the geometry and dynamics of the merger, as well as using the merger to constrain self-interacting dark matter. We find that the system is dominated by two subclusters of comparable richness with a projected separation of 6.9'^{+0.7}_{-0.5} (1.3^{+0.13}_{-0.10} Mpc). We find that the north and south subclusters have similar redshifts of z=0.188 with a relative line-of-sight velocity difference of 69+/-190 km/s. We also find that north and south subclusters have velocity dispersions of 1160^{+100}_{-90} km/s and 1080^{+100}_{-70} km/s, respectively. These correspond to masses of 16.1^{+4.6}_{-3.3}x10^14 M_sun and 13.0^{+4.0}_{-2.5}x10^14 M_sun, respectively. While velocity dispersion measurements of merging clusters can be biased we believe the bias in this system to be minor due to the large projected separation and nearly plane-of-sky merger configuration. CIZA J2242.8+5301 is a relatively clean dissociative cluster merger with near 1:1 mass ratio, which makes it an ideal merger for studying merger associated physical phenomena.

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William A. Dawson, M. James Jee, Andra Stroe, Y. Karen Ng, Nathan Golovich, David Wittman, David Sobral, Marcus Bruggen, H. J. A. Rottgering, R. J. van Weeren. 2014-10-10. MC^2: Galaxy Imaging and Redshift Analysis of the Merging Cluster CIZA J2242.8+5301. https://doi.org/10.1088/0004-637x%2F805%2F2%2F143

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