paper

Cluster Mergers as Triggers of Star Formation and Radio Emission: A Comparative Study of the Rich Clusters A2125 and A2645

arXiv:astro-ph/9905004 · doi:10.1086/300974

Abstract

We report a detailed optical study of the clusters Abell 2125 and 2645. Both clusters have z=0.25 and richness class 4, yet contrast strongly in blue fraction and radio galaxy population. We find 27 spectroscopically confirmed radio galaxies in the blue cluster, A2125 and only four in A2645. The excess radio population in A2125 occurs entirely at L(20cm) < 10^23 W/Hz, where one expects star-formation to be responsible for the radio emission. Most of the radio galaxies have optical properties consistent with types later than E/S0, but emission lines weaker than would be expected for the SFR's implied by the radio emission. Thus we suspect dust obscuration is important. The cluster- cluster merger in A2125 seems likely to play a part in these phenomena.

24 pages, including 4 tables and 9 figures. Figures 3 and 4 in JPG format. Full-resolution PS versions available at: ftp://wombat.phys.unm.edu/pub/A2125/fig3.ps.gz and ftp://wombat.phys.unm.edu/pub/A2125/fig4.ps.gz Accepted for publication in the Astronomical Journal

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