Speaker
Stefan Reißl
(Christian-Albrechts-Universität zu Kiel, Institut für Theoretische Physik und Astrophysik)
Description
Magnetic fields in the interstellar medium (ISM) critically affect many astrophysical processes in various environments and scales, such as the collapse of molecular clouds, the formation of jets, and accretion of matter through circumstellar disks. However, vital questions still remain unanswered due to an apparently complex structure of the magnetic field on various scales and so far rather limited constraints from line-of-sight polarization measurements.
With the help of scattering and dichroic polarization mechanisms of stellar light and dust reemission radiation we study both, the properties of dust particles and the effects of magnetic fields in the ISM itself. Various dust grain properties, alignment mechanisms and advanced magneto-hydro dynamic (MHD) scenarios are considered to offer intensity and polarization maps for the analysis of a broad variety of observed ISM configurations. Processed ideal as well as more realistic MHD scenarios reveal the advantages and the potential of linear but also of circular polarization measurements as a promising source of additional information.
We present first results of synthetic continuum polarization maps resulting from post-processed MHD simulations combined with a model of non-spherical imperfectly aligned dust grains. In contrast to ideal scenarios, complex temperature, density distributions as well as corresponding magnetic field configurations lead to a wide variation of unexpected polarization effects and are often intuitively no longer accessible. These effects allow us to disentangle ambiguities in the interpretation of two-dimensional polarization maps and thus will subsequently lead to a more detailed understanding of the magnetic field morphology based on dedicated multi-scale, multi-wavelength polarization measurements.
Author
Stefan Reißl
(Christian-Albrechts-Universität zu Kiel, Institut für Theoretische Physik und Astrophysik)