Letter to the Editor

Improving the identification of high-z Herschel sources with position priors and optical/NIR and FIR/mm photometric redshifts ^*

¹ Departamento de Astrofísica, Facultad de CC. Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain e-mail: pgperez@astrax.fis.ucm.es
² Steward Observatory, The University of Arizona, 933 N Cherry Avenue, Tucson, AZ 85721, USA
³ Laboratoire d'Astrophysique de Marseille, CNRS – Université Aix-Marseille, 38 Rue Frédéric Joliot-Curie, 13388 Marseille, France
⁴ Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
⁵ Onsala Space Observatory, Chalmers University of Technology, 439 92 Onsala, Sweden
⁶ Herschel Science Centre, ESAC, ESA, PO Box 50727, 28080 Madrid, Spain
⁷ California Institute of Technology, Pasadena, CA 91125, USA
⁸ Jet Propulsion Laboratory, Pasadena, CA 91109, USA
⁹ Laboratoire d'Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 14 Av. Edouard Belin, 31400 Toulouse, France
¹⁰ Department of Astronomy, University of Florida, Gainesville, FL 32611-2055, USA
¹¹ Department of Physics & Astronomy, Ohio University, Clippinger Labs 251B, Athens, OH 45701, USA
¹² Observatoire de Paris, LERMA, 61 Av. de l'Observatoire, 75014 Paris, France
¹³ Laboratoire d'Astrophysique de Marseille, Observatoire Astronomique de Marseille-Provence, 2 Place Le Verrier, 13248 Marseille, France
¹⁴ Geneva Observatory, University of Geneva, 51 Ch. des Maillettes, 1290 Versoix, Switzerland
¹⁵ NASA Herschel Science Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125, USA
¹⁶ UK Astronomy Technology Centre, Science and Technology Facilities Council, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
¹⁷ Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
¹⁸ Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany
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

Received: 31 March 2010
Accepted: 6 May 2010

Abstract

We present preliminary results about the detection of high redshift (U)LIRGs in the Bullet cluster field by the PACS and SPIRE instruments within the Herschel Lensing Survey (HLS) Program. We describe in detail a photometric procedure designed to recover robust fluxes and deblend faint Herschel sources near the confusion noise. The method is based on the use of the positions of Spitzer/MIPS 24 μm sources as priors. Our catalogs are able to reliably (5σ) recover galaxies with fluxes above 6 and 10 mJy in the PACS 100 and 160 μm channels, respectively, and 12 to 18 mJy in the SPIRE bands. We also obtain spectral energy distributions covering the optical through the far-infrared/millimeter spectral ranges of all the Herschel detected sources, and analyze them to obtain independent estimations of the photometric redshift based on either stellar population or dust emission models. We exemplify the potential of the combined use of Spitzer position priors plus independent optical and IR photometric redshifts to robustly assign optical/NIR counterparts to the sources detected by Herschel and other (sub-)mm instruments.