Letter to the Editor

The Herschel Virgo Cluster Survey ^*

VI. The far-infrared view of M 87

¹ Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, 9000 Gent, Belgium e-mail: maarten.baes@ugent.be
² INAF-Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
³ National Observatory of Athens, I. Metaxa and Vas. Pavlou, P. Penteli, 15236 Athens, Greece
⁴ National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA, 22903-2475, USA
⁵ Department of Physics and Astronomy, Cardiff University, The Parade, Cardiff, CF24 3AA, UK
⁶ Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ, UK
⁷ INAF-Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
⁸ Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, Postfach 1312, 85741, Garching, Germany
⁹ Astronomical Institute, Ruhr-University Bochum, Universitaetsstr. 150, 44780 Bochum, Germany
¹⁰ Laboratoire d'Astrophysique de Marseille, UMR 6110 CNRS, 38 rue F. Joliot-Curie, 13388 Marseille, France
¹¹ NASA Herschel Science Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125, USA
¹² ESO, Alonso de Cordova 3107, Vitacura, Santiago, Chile
¹³ Università di Milano-Bicocca, piazza della Scienza 3, 20100, Milano, Italy
¹⁴ CAAUL, Observatório Astronómico de Lisboa, Universidade de Lisboa, Tapada da Ajuda, 1349-018, Lisboa, Portugal
¹⁵ Institut d'Astrophysique Spatiale (IAS), Batiment 121, Universite Paris-Sud 11 and CNRS, 91405 Orsay, France
¹⁶ Laboratoire AIM, CEA/DSM – CNRS – Université Paris Diderot, Irfu/Service d'Astrophysique, 91191 Gif-sur-Yvette, France
¹⁷ INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, via Fosso del Cavaliere 100, 00133, Roma, Italy
¹⁸ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
¹⁹ Max-Planck-Institut für Astronomie, Koenigstuhl 17, 69117 Heidelberg, Germany

Received: 30 March 2010
Accepted: 2 May 2010

Abstract

The origin of the far-infrared emission from the nearby radio galaxy M 87 remains a matter of debate. Some studies find evidence of a far-infrared excess due to thermal dust emission, whereas others propose that the far-infrared emission can be explained by synchrotron emission without the need for an additional dust emission component. We present Herschel PACS and SPIRE observations of M 87, taken as part of the science demonstration phase observations of the Herschel Virgo Cluster Survey. We compare these data with a synchrotron model based on mid-infrared, far-infrared, submm and radio data from the literature to investigate the origin of the far-infrared emission. Both the integrated SED and the Herschel surface brightness maps are adequately explained by synchrotron emission. At odds with previous claims, we find no evidence of a diffuse dust component in M 87, which is not unexpected in the harsh X-ray environment of this radio galaxy sitting at the core of the Virgo cluster.