Letter to the Editor

The far-infrared/submillimeter properties of galaxies located behind the Bullet cluster ^*,**

¹ Steward Observatory, University of Arizona, 933 N. Cherry Ave, Tucson, AZ 85721, USA e-mail: mrex@as.arizona.edu

² Departamento de Astrofísica, Facultad de CC. Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain

³ California Institute of Technology, Pasadena, CA 91125, USA

⁴ Jet Propulsion Laboratory, Pasadena, CA 91109, USA

⁵ Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE), Luis Enrique Erro No.1, Tonantzintla, Puebla, CP 72840, Mexico

⁶ Department of Astronomy, University of Florida, Gainesville, FL 32611-2055, USA

⁷ NASA Herschel Science Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125, USA

⁸ Onsala Space Observatory, Chalmers University of Technology, 439 92 Onsala, Sweden

⁹ Laboratoire d'Astrophysique de Marseille, CNRS – Université Aix-Marseille, 38 Rue Frédéric Joliot-Curie, 13388 Marseille Cedex 13, France

¹⁰ Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK

¹¹ Herschel Science Centre, ESAC, ESA, PO Box 78, Villanueva de la Cañada, 28691 Madrid, Spain

¹² Laboratoire d'Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 14 Av. Edouard Belin, 31400 Toulouse, France

¹³ Observatoire de Paris, LERMA, 61 Av. de l'Observatoire, 75014 Paris, France

¹⁴ Geneva Observatory, University of Geneva, 51, Ch. des Maillettes, 1290 Versoix, Switzerland

¹⁵ UK Astronomy Technology Centre, Science and Technology Facilities Council, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK

¹⁶ Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK

¹⁷ Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany

¹⁸ Institut d'Astrophysique de Paris, CNRS and Université Pierre et Marie Curie, 98bis Boulevard Arago, 75014 Paris, France

¹⁹ Department of Astronomy, University of Padova, Vicolo dell'Osservatorio 3, 35122 Padova, Italy

²⁰ School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK

²¹ Sterrewacht Leiden, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

²² Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309, USA

²³ Nobeyama Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Minamisaku, Nagano 384-1305, Japan

²⁴ Institute of Astronomy, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan

²⁵ Research Center for the Early Universe, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan

²⁶ Department of Physics, Illinois Wesleyan University, Bloomington, IL 61702-2900, USA

²⁷ Department of Physics & Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104, USA

²⁸ Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003, USA


Received: 1 April 2010
Accepted: 18 May 2010

Abstract

The Herschel Lensing Survey (HLS) takes advantage of gravitational lensing by massive galaxy clusters to sample a population of high-redshift galaxies which are too faint to be detected above the confusion limit of current far-infrared/submillimeter telescopes. Measurements from 100–500 μm bracket the peaks of the far-infrared spectral energy distributions of these galaxies, characterizing their infrared luminosities and star formation rates. We introduce initial results from our science demonstration phase observations, directed toward the Bullet cluster (1E0657-56). By combining our observations with LABOCA 870 μm and AzTEC 1.1 mm data we fully constrain the spectral energy distributions of 19 MIPS 24 μm-selected galaxies which are located behind the cluster. We find that their colors are best fit using templates based on local galaxies with systematically lower infrared luminosities. This suggests that our sources are not like local ultra-luminous infrared galaxies in which vigorous star formation is contained in a compact highly dust-obscured region. Instead, they appear to be scaled up versions of lower luminosity local galaxies with star formation occurring on larger physical scales.