Cosmic Ray Driven Galactic Winds

Abstract:
Numerical models of the multiphase interstellar medium (ISM) in disk galaxies have recently addressed the importance of rays (CRs) and magnetic fields for the physics of the ISM. These components of the ISM contribute significantly to the total pressure and thus influence the large scale distribution of the ISM and its evolution. Observational evidence from radio-continuum studies of edge-on galaxies on magnetic field strength and structure will be presented and the cosmic ray propagation in galactic halos will be discussed. Observations from the CHANG- ES (Continuum HAlos in Nearby Galaxies – an EVLA Survey; PI J. Irwin) project benefit from complementary LOFAR observations. The lowest frequencies provide additional constraints on the extent of magnetic fields in galactic halos and on the synchrotron losses of the CR electrons.

The figure shows a composite image revealing the magnetic field of starburst galaxy NGC4666.

Credit: Y. Stein (Ruhr U.); NRAO/AUI/NSF; ESO/J. Dietrich; C. Vargas. Data from NRAO, MPG/ESO 2.2m, APO 3.5m.