EDP Sciences
Free access
Volume 485, Number 3, July III 2008
Page(s) L25 - L28
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200810048
Published online 27 May 2008

A&A 485, L25-L28 (2008)
DOI: 10.1051/0004-6361:200810048


LABOCA and MAMBO-2 imaging of the dust ring of the Sombrero galaxy (NGC 4594)

C. Vlahakis1, M. Baes2, G. Bendo3, and A. Lundgren4

1  Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
    e-mail: vlahakis@strw.leidenuniv.nl
2  Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, 9000 Gent, Belgium
3  Astrophysics Group, Imperial College, Blackett Laboratory, Prince Consort Road, London SW7 2AZ, UK
4  ESO, Casilla 19001, Santiago 19, Chile

Received 24 April 2008 / Accepted 16 May 2008

The Sombrero galaxy (NGC 4594) is an Sa galaxy with a symmetric dust ring. We have used the Large APEX BOlometer CAmera (LABOCA) at 870 $\mu$m and the MAx-Planck Millimeter BOlometer (MAMBO-2) at 1.2 mm to detect the dust ring for the first time at submillimetre and millimetre wavelengths. We have constructed a model of the galaxy to separate the active galactic nucleus (AGN) and dust ring components. The ring radius at both 870 $\mu$m and 1.2 mm agrees well with the radius determined from optical absorption and atomic gas studies. The spectral energy distribution of the ring is well fitted by a single grey-body with dust emissivity index $\beta=2$ and a dust temperature Td=18.4 K. The dust mass of the ring is found to be $1.6\pm0.2\times 10^7$ $M_\odot$ which, for a Galactic gas-to-dust ratio, implies a gas mass that is consistent with measurements from the literature.

Key words: galaxies: active -- galaxies: individual: NGC 4594 -- galaxies: ISM -- galaxies: nuclei -- submillimeter -- ISM: dust, extinction

© ESO 2008