LoCuSS: Shedding new light on the massive lensing cluster Abell 1689 – the view from Herschel

• Published in: Astronomy and astrophysics (Berlin) 2010-07, Vol.518 (1), p.L19
• Main Authors: Haines, C. P., Smith, G. P., Pereira, M. J., Egami, E., Moran, S. M., Hardegree-Ullman, E., Rawle, T. D., Rex, M.
• Format: Article
• Language: English
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; galaxies: clusters: individual: Abell 1689; galaxies: star formation; Galaxy: evolution; infrared: galaxies
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/201014692

We present wide-field Herschel/PACS observations of A 1689, a massive galaxy cluster at z = 0.1832, from our open time key programme. We detect 39 spectroscopically confirmed 100 μm-selected cluster members down to 1.5×1010 $L_{\odot}$. These galaxies are forming stars at rates in the range 1–10 $M_{\odot}$/yr, and appear to comprise two distinct populations: two-thirds are unremarkable blue, late-type spirals found throughout the cluster; the remainder are dusty red sequence galaxies whose star formation is heavily obscured with A(Hα)~2 mag and are found only in the cluster outskirts. The specific-SFRs of these dusty red galaxies are lower than the blue late-types, suggesting that the former are in the process of being quenched, perhaps via pre-processing, the unobscured star formation being terminated first. We also detect an excess of 100 μm-selected galaxies extending ~6 Mpc in length along an axis that runs NE-SW through the cluster center at $\ga$95% confidence. Qualitatively this structure is consistent with previous reports of substructure in X-ray, lensing, and near-infrared maps of this cluster, further supporting the view that this cluster is a dynamically active, merging system.