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

摘要

The Sombrero galaxy (NGC 4594) is an Sa galaxy with a symmetric dust ring. Wehave used the Large APEX BOlometer CAmera (LABOCA) at 870 micron and theMAx-Planck Millimeter BOlometer (MAMBO-2) at 1.2 mm to detect the dust ring forthe first time at submillimetre and millimetre wavelengths. We have constructeda model of the galaxy to separate the active galactic nucleus (AGN) and dustring components. The ring radius at both 870 micron and 1.2 mm agrees well withthe radius determined from optical absorption and atomic gas studies. Thespectral energy distribution of the ring is well fitted by a single grey-bodywith dust emissivity index beta=2 and a dust temperature T_d=18.4 K. The dustmass of the ring is found to be 1.6\pm0.2x10^7Msun which, for a Galacticgas-to-dust ratio, implies a gas mass that is consistent with measurements fromthe literature.