Poster Presentation
A Comparison of Synthetic Polarization Maps of Supernova-Driven Turbulence with Planck Observations
Presenter: Miikka Väisälä (Academia Sinica Institute of Astronomy and Astrophysics)
We have explored dust polarization measurements with synthetic observations from kiloparsec-scale magnetohydrodynamic (MHD) models, with an uniform grid with 4 pc spatial resolution, where non-uniform magnetic field was generated at both large and small scales by a supernova- and shear-driven dynamo. In the model, the hot shocked gas created by supernovae was taken into account, which we have deemed significant for supernova-driven turbulent flows.
We computed synthetic maps polarization with radiative transfer calculations, where we put the observer inside the model volume. We particularly looked into hydrogen column density, polarization fraction and polarization angle dispersion. and explored how they were dependent on the properties of our MHD model. Such properties included large- and small-scale magnetic fields and their relative orientation, and shocks driven by supernovae.
Our synthetic observations show similar filament-like structures in polarization angle dispersion, as observed by Planck satellite. We witness anticorrelation between polarization fraction and polarization angle dispersion, shown also by Planck, which we relate to the turbulent fluctuations of the magnetic field. We also see that polarization fraction decreases as a function of column density, which is contributed by cumulative effects of turbulence near the galactic midplane. In addition, we show that the alignment of the large-scale magnetic field has visible influence on polarization fraction and angle dispersion: a large-scale magnetic field aligned with the plane of sky decreases the amount of polarization angle dispersion. The polarization properties do not correlate with supernova-driven shocks directly.
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