Dynamical galactic halos are of high interest for models of magnetic fields in galaxies, and their physics has returned into the focus of research activities during recent years. These activities comprise both the collection of a wealth of new data based on new or upgraded observational facilities such as the Jansky Very Large Array (JVLA) or the Low Frequency Array (LOFAR) as well as the development of advanced magnetohydrodynamical (MHD) simulation codes. Most starforming spiral galaxies seen edge-on exhibit very extended radio halos. The extent of these radio continuum halos directly indicates the presence of cosmic-ray electrons in magnetic fields.
Still missing, as opposed to analytical models, is a numerical state-of-the-art MHD modeling of turbulent dynamical halos. Neither dynamo models nor wind models have the turbulent magnetic field self-consistently included in a three-dimensional and time-dependent fashion that must include not only the gravitational fields of the disk and the bulge, but also that of a (possibly non-spherical) dark halo.
The objectives of the project aim to answer the following key science questions:
During the first 4-year phase we will, using the MHD code Cronos, perform simulations of MHD turbulence in dynamical halos for different scenarios: namely for starburst galaxies with and without the gravitational effect of dark matter, and, correspondingly, for supersonic winds vs. subsonic breezes. These models will be compared to observations. For this comparison we will analyze the magnetic field structure, the relevance of the turbulent field, and the related cosmic-ray electron distributions as derived from new radio observations obtained by new or upgraded facilities. These observations cover a larger frequency range and larger bandwidth than previous instruments. Finally, the use of the rotation measure (RM) synthesis technique will allow for an improved reconstruction of magnetic field properties.
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Last update: Sep 07, 2022
