Radio polarization and sub-mm observations of the Sombrero galaxy (NGC 4594) - Large-scale magnetic field configuration and dust emission

摘要

We observed the nearby early-type spiral galaxy NGC 4594 (M 104, Sombrerogalaxy) with the Very Large Array at 4.86 GHz, with the Effelsberg 100-mtelescope at 8.35 GHz as well as with the Heinrich Hertz Telescope at 345 GHzin radio continuum. The 4.86 and 8.35 GHz data contain polarization informationand hence information about the magnetic fields: we detected a large-scalemagnetic field which is to our knowledge the first detection of a large-scalemagnetic field in an Sa galaxy in the radio range. The magnetic fieldorientation in M104 is predominantly parallel to the disk but has also verticalcomponents at larger z-distances from the disk. This field configuration istypical for normal edge-on spiral galaxies. The 345 GHz data pertain to thecold dust content of the galaxy. Despite the optical appearance of the objectwith the huge dust lane, its dust content is smaller than that of morelate-type spirals.