Letter to the Editor

Herschel photometry of brightest cluster galaxies in cooling flow clusters ^*,**

¹ Institute for Computational Cosmology, Department of Physics, Durham University, Durham, DH1 3LE, UK e-mail: alastair.edge@durham.ac.uk
² Leiden Observatory, Leiden University, PB 9513, Leiden 2300 RA, The Netherlands
³ Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, Rochester, NY 14623, USA
⁴ Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305-4085, USA
⁵ Max-Planck-Institut für extraterrestrische Physik, 85748 Garching, Germany
⁶ University of Michigan, Dept. of Astronomy, Ann Arbor, MI 48109, USA
⁷ H H Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, UK
⁸ Observatoire de Paris, LERMA, CNRS, 61 Av. de l'Observatoire, 75014 Paris, France
⁹ Institute of Astronomy, Madingley Rd., Cambridge, CB3 0HA, UK
¹⁰ Michigan State University, Physics and Astronomy Dept., East Lansing, MI 48824-2320, USA
¹¹ Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721, USA
¹² Department of Physics, University of Kentucky, Lexington, KY 40506, USA
¹³ School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
¹⁴ Department of Physics & Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, N2L 3G1 Ontario, Canada
¹⁵ Department of Physics, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623-5603, USA
¹⁶ Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627, USA
¹⁷ Department of Astronomy, University of Virginia, PO Box 400325, Charlottesville, VA 22904-4325, USA
¹⁸ School of Physics, University of Melbourne, Victoria 3010, Australia
¹⁹ ASTRON, Netherlands Institute for Radio Astronomy, PO Box 2, 7990 AA Dwingeloo, The Netherlands

Received: 30 March 2010
Accepted: 2 May 2010

Abstract

The dust destruction timescales in the cores of clusters of galaxies are relatively short given their high central gas densities. However, substantial mid-infrared and sub-mm emission has been detected in many brightest cluster galaxies. In this letter we present Herschel PACS and SPIRE photometry of the brightest cluster galaxy in three strong cooling flow clusters, A1068, A2597 and Zw3146. This photometry indicates that a substantial mass of cold dust is present (> 3×10⁷ ) at temperatures significantly lower (20–28 K) than previously thought based on limited MIR and/or sub-mm results. The mass and temperature of the dust appear to match those of the cold gas traced by CO with a gas-to-dust ratio of 80–120.