Letter to the Editor

Herschel-ATLAS: Blazars in the science demonstration phase field ^*

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SISSA, via Beirut 2–4, 34014 Trieste, Italy e-mail: gnuevo@sissa.it
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INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
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ESO, Karl-Schwarzschild-Str.2, 85748, Garching, Germany
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INAF, Osservatorio Astronomico di Trieste, via Tiepolo 11, 34143, Trieste, Italy
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Department of Physics & Astronomy, University of California, Irvine, CA 92697, USA
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Argelander Institute for Astronomy, University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
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Department of Physics, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
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Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710, Australia
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School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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School of Physics and Astronomy, Cardiff University, The Parade, Cardiff, CF24 3AA, UK
¹¹ 
Centre for Astrophysics, Science & Technology Research Institute, University of Hertfordshire, Hatfield, AL10 9AB, UK
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Astrophysics, Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
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Instituto de Física de Cantabria (CSIC-UC), Avda. los Castros s/n, 39005 Santander, Spain
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Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE), Luis Enrique Erro No. 1, Tonantzintla, Puebla, C.P. 72840, Mexico
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Dipartimento di Fisica, Universita Tor Vergata, via Ricerca Scientifica 1, 00133 Roma, Italy
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Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
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Astrophysics Branch, NASA Ames Research Center, Mail Stop 245-6, Moffett Field, CA 94035, USA
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Department of Physics & Astronomy, The Open University, Milton Keynes MK7 6BJ, UK
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Department of Astronomy, University of Padova, Vicolo dellOsservatorio 3, 35122 Padova, Italy
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Division of Physics, Mathematics & Astronomy, California Institute of Technology, Mail Code 59-33, Pasadena, CA 91125
²¹ 
Space Science Department, Rutherford Appleton Laboratory, Chilton, UK
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Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, 9000 Gent, Belgium
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Laboratoire d'Astrophysique de Marseille, UMR6110 CNRS, 38 rue F. Joliot-Curie, 13388 Marseille, France
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Instituto de Astrofísica de Canarias (IAC), 38200 La Laguna, Tenerife, Spain
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Departamento de Astrofísica, Universidad de La Laguna (ULL), 38205 La Laguna, Tenerife, Spain
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Astrophysics Group, Imperial College, Blackett Laboratory, Prince Consort Road, London SW7 2AZ, UK
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National Radio Astronomy Observatory, PO Box 2, Green Bank, WV 24944, USA
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UK Astronomy Technology Center, Royal Observatory Edinburgh, Edinburgh, EH9 3HJ, UK
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Institut d'Astrophysique Spatiale (IAS), Bâtiment 121, 91405 Orsay; Université Paris-Sud 11 and CNRS (UMR 8617), France
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Herschel Science Centre, ESAC, ESA, PO Box 78, Villanueva de la Cañada, 28691 Madrid, Spain

Received: 31 March 2010
Accepted: 5 May 2010

Abstract



To investigate the poorly constrained sub-mm counts and spectral properties of blazars we searched for these in the Herschel-ATLAS (H-ATLAS) science demonstration phase (SDP) survey catalog.

We cross-matched 500 μm sources brighter than 50 mJy with the FIRST radio catalogue. We found two blazars, both previously known. Our study is among the first blind blazar searches at sub-mm wavelengths, i.e., in the spectral regime where little is still known about the blazar SEDs, but where the synchrotron peak of the most luminous blazars is expected to occur. Our early results are consistent with educated extrapolations of lower frequency counts and question indications of substantial spectral curvature downwards and of spectral upturns at mm wavelengths. One of the two blazars is identified with a Fermi/LAT γ-ray source and a WMAP source. The physical parameters of the two blazars are briefly discussed. These observations demonstrate that the H-ATLAS survey will provide key information about the physics of blazars and their contribution to sub-mm counts.