The Relation between Cool Cluster Cores and Herschel-detected Star Formation in Brightest Cluster Galaxies

Creators: Rawle, T. D.; Edge, A. C.; Egami, E.; Rex, M.; Smith, G. P.; Altieri, B.; Fiedler, A.; Haines, C. P.; Pereira, M. J.; Pérez-González, P. G.; Portouw, J.; Valtchanov, I.; Walth, G.; van der Werf, P. P.; Zemcov, M.

Abstract

We present far-infrared (FIR) analysis of 68 brightest cluster galaxies (BCGs) at 0.08 < z < 1.0. Deriving total infrared luminosities directly from Spitzer and Herschel photometry spanning the peak of the dust component (24-500 μm), we calculate the obscured star formation rate (SFR).22^(+6.2)_(–5.3)% of the BCGs are detected in the far-infrared, with SFR = 1-150 M_☉ yr^(–1). The infrared luminosity is highly correlated with cluster X-ray gas cooling times for cool-core clusters (gas cooling time <1 Gyr), strongly suggesting that the star formation in these BCGs is influenced by the cluster-scale cooling process. The occurrence of the molecular gas tracing Hα emission is also correlated with obscured star formation. For all but the most luminous BCGs(L_(TIR) > 2 × 10^(11) L_☉), only a small (≾0.4 mag) reddening correction is required for SFR(Hα) to agree with SFR_(FIR). The relatively low Hα extinction (dust obscuration), compared to values reported for the general star-forming population, lends further weight to an alternate (external) origin for the cold gas. Finally, we use a stacking analysis of non-cool-core clusters to show that the majority of the fuel for star formation in the FIR-bright BCGs is unlikely to originate from normal stellar mass loss.

Additional Information

© 2012 American Astronomical Society. Received 2011 November 18; accepted 2012 January 3; published 2012 February 10. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. This work is partially based on observations made with the Herschel Space Observatory, a European Space Agency Cornerstone Mission with significant participation by NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. We also thank the HSC and NHSC consortia for support with data reduction. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. G.P.S. acknowledges support from the Royal Society.

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