Volume 518, July-August 2010
Herschel: the first science highlights
|Number of page(s)||4|
|Published online||16 July 2010|
Letter to the Editor
LoCuSS: Shedding new light on the massive lensing cluster Abell 1689 – the view from Herschel *
School of Physics and Astronomy, University of Birmingham,
Edgbaston, B15 2TT, UK e-mail: firstname.lastname@example.org
2 Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
3 Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
4 Rensselaer Polytechnic Institute (RPI) 110 Eighth Street, Troy, NY 12180, USA
Accepted: 3 May 2010
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 . These galaxies are forming stars at rates in the range 1–10 /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 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.
Key words: galaxies: clusters: individual: Abell 1689 / Galaxy: evolution / galaxies: star formation / infrared: galaxies
© ESO, 2010
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