EAS Publications Series
Volume 56, 2012The Role of the Disk-Halo Interaction in Galaxy Evolution: Outflow vs. Infall?
|Page(s)||51 - 59|
|Section||Structure and Components of the ISM in Galaxies|
|Published online||17 September 2012|
Miguel A. de Avillez (ed)
EAS Publications Series, 56 (2012) 51–59
Magnetic Fields in Disks and Halos of Galaxies
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
Radio synchrotron emission, its polarization and its Faraday rotation are powerful tools to study the strength and structure of interstellar magnetic fields. Total fields in gas-rich spiral arms and bars of nearby galaxies have strengths of 20–30 μG and are dynamically important. Ordered fields with spiral structure exist in grand-design, flocculent and even irregular galaxies. The strongest ordered fields of 5–10 μG are found in interarm regions, sometimes forming “magnetic spiral arms”. Faraday rotation sometimes reveals large-scale patterns which are signatures of coherent fields generated by dynamos, but in most galaxies the field has a complicated structure. – Magnetic fields with X-shaped patterns are observed in radio halos around edge-on galaxies. The synchrotron scale height allows to measure the mean outflow velocity, which seems to increase with the star-formation rate.
© EAS, EDP Sciences, 2012