Star formation in the massive cluster merger Abell 2744
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2014
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Royal Astronomical Society
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Abstract
We present a comprehensive study of star- orming (SF) galaxies in the HST Frontier Field recent cluster merger A2744 (z = 0.308). Wide-field, ultraviolet–infrared (UV–IR) imaging enables a direct constraint of the total star formation rate (SFR) for 53 cluster galaxies, with SFR_(UV+IR) = 343 ± 10 M_⊙ yr^(−1) . Within the central 4 arcmin (1.1 Mpc) radius, the integrated SFR is complete, yielding a total SFR_(UV+IR) = 201±9 M_⊙ yr^(−1) . Focussing on obscured star formation, this core region exhibits a total SFR^(IR) = 138 ± 8 M_⊙ yr^(−1), a mass-normalised SFR_(IR) of ΣSFR = 11.2 ± 0.7 M_⊙ yr^(−1) per 10^(14) M_⊙ and a fraction of IR-detected SF galaxies f_(SF) = 0.080^(+0.010)_(−0.037). Overall, the cluster population at z ∼ 0.3 exhibits significant intrinsic scatter in IR properties (total SFRIR, Tdust distribution) apparently unrelated to the dynamical state: A2744 is noticeably different to the merging Bullet cluster, but similar to several relaxed clusters. However, in A2744 we identify a trail of SF sources including jellyfish galaxies with substantial unobscured SF due to extreme stripping (SFR_(UV)/SFR_(IR) up to 3.3). The orientation of the trail, and of material stripped from constituent galaxies, indicates that the passing shock front of the cluster merger was the trigger. Constraints on star formation from both IR and UV are crucial for understanding galaxy evolution within the densest environments
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© 2013 RAS, MNRAS.
T. Rawle is supported by a European Space Agency (ESA) Research Fellowship at the European Space Astronomy Centre (ESAC), in Madrid, Spain. J. Santos has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement 267251 “Astronomy Fellowships in Italy” (AstroFIt). C. Haines was funded by CONICYT Anillo project ACT-1122. N. Okabe was supported by the World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan. The authors would particularly like to thank A. Cava, F. Combes and I. Smail for useful discussion and M. Owers for providing the combined image from the Chandra X-ray Observatory.
This work is based on observations made with the Herschel Space Observatory, an ESA Cornerstone Mission with significant participation by NASA.
M. Rex and G. Walth were visiting astronomers for programme 2011A-3095 (PI: T. Rawle) at CTIO, NOAO, which is operated by AURA, under contract with NSF.
Also based on observations made with the NASA/ESA Hubble Space Telescope, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programme #11689 and HFF DD programmes #13389,13495. This publication also uses data products from the Wide-field Infrared Survey Explorer (WISE), which is a joint project of UCLA and JPL, Caltech, funded by NASA. We made use of a private version of the Rainbow Cosmological Surveys Database, operated by the Universidad Complutense de Madrid (UCM).