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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - MC2
T2 - Boosted AGN and star formation activity in CIZA J2242.8+5301, a massive post-merger cluster at z = 0.19
AU - Sobral, David
AU - Stroe, Andra
AU - Dawson, William A.
AU - Wittman, David
AU - James Jee, M.
AU - Röttgering, Huub
AU - van Weeren, Reinout J.
AU - Brüggen, Marcus
PY - 2015/6/11
Y1 - 2015/6/11
N2 - 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 (<30 × lower than all other star-forming galaxies outside the cluster) and/or significant contribution from supernovae, respectively. All cluster star-forming galaxies near the cluster centre show evidence of significant outflows (blueshifted Na D ~200-300 km s-1), likely driven by supernovae. Strong outflows are also found for the cluster Hα active galactic nucleus (AGN). Hα star-forming galaxies in the merging cluster follow the z ~ 0 mass-metallicity relation, showing systematically higher metallicity (~0.15-0.2 dex) than Hα emitters outside the cluster (projected R > 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.
AB - 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 (<30 × lower than all other star-forming galaxies outside the cluster) and/or significant contribution from supernovae, respectively. All cluster star-forming galaxies near the cluster centre show evidence of significant outflows (blueshifted Na D ~200-300 km s-1), likely driven by supernovae. Strong outflows are also found for the cluster Hα active galactic nucleus (AGN). Hα star-forming galaxies in the merging cluster follow the z ~ 0 mass-metallicity relation, showing systematically higher metallicity (~0.15-0.2 dex) than Hα emitters outside the cluster (projected R > 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.
KW - Cosmology: observations
KW - galaxies: clusters: general
KW - Galaxies: clusters: individual: CIZA J2242.8+5301
KW - Galaxies: evolution
KW - Intergalactic medium
KW - Large-scale structure of Universe
U2 - 10.1093/mnras/stv521
DO - 10.1093/mnras/stv521
M3 - Journal article
VL - 450
SP - 630
EP - 645
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 1
ER -