1. MC2: boosted AGN and star formation activity in CIZA J2242.8+5301, a massive post-merger cluster at z = 0.19
- Author
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Sobral, David, Stroe, Andra, Dawson, William A, Wittman, David, Jee, M James, Röttgering, Huub, van Weeren, Reinout J, and Brüggen, Marcus
- Subjects
galaxies: clusters: general ,galaxies: clusters: individual: CIZA J2242.8+5301 ,galaxies: evolution ,intergalactic medium ,cosmology: observations ,large-scale structure of Universe ,astro-ph.GA ,astro-ph.CO ,astro-ph.HE ,Astronomical and Space Sciences ,Astronomy & Astrophysics - Abstract
Cluster mergers may play a fundamental role in the formation and evolution of cluster galaxies. Stroe et al. revealed unexpected overdensities of candidate Hα emitters near the ~1-Mpc-wide shock fronts of the massive (~2 × 1015 M⊙) 'Sausage' merging cluster, CIZA J2242.8+5301. We used the Keck/Deep Imaging Multi-Object Spectrograph and the William Herschel Telescope/AutoFib2+WYFFOS to confirm 83 Hα emitters in and around the merging cluster. We find that cluster star-forming galaxies in the hottest X-ray gas and/or in the cluster subcores (away from the shock fronts) show high [S II]6716/[S II]6761 and high [S II] 6716/Hα, implying very low electron densities ( 2.5 Mpc). This suggests that the shock front may have triggered remaining metal-rich gas which galaxies were able to retain into forming stars. Our observations show that the merger of impressively massive (~1015 M⊙) clusters can provide the conditions for significant star formation and AGN activity, but, as we witness strong feedback by star-forming galaxies and AGN (and given how massive the merging cluster is), such sources will likely quench in a few 100 Myr.
- Published
- 2015