Highly inclined galaxies - galactic haloes
The observations of highly inclined galaxies yield an unique possibility to trace the magnetic fields high in the halo and to study the disk-halo interactions. This image (VLA at 6cm) shows the distribution of the polarized intensity (blue) with B-vectors of the same quantity. The underlying image is the Ha picture of the galaxy. Note the X-shaped distribution of polarized intensity, followed also by the directions of the sky-projected magnetic fields (Faraday rotation in the halo is negligible at this frequency). For details, see Tuellmann, Dettmar, Soida et al.(2000)
This is the map of Faraday rotation of NGC 5775 between 3.6 cm and 6cm using the VLA maps. Blue/green colours mean negative rotation measures while red/purple shows regions of positive rotations. Note that there are no reversals across the galaxy's plane, as expected for the quadrupole-type magnetic fields. Results will appear soon in Astron. Astrophys.