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EPoS |
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EPoS Contribution
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MHD simulations of molecular clouds and synthetic dust polarisation maps: What can we learn from it?
Daniel Seifried U Köln, Cologne, DE | |
| I present results of fully self-consistent synthetic dust polarisation maps created with POLARIS of simulated molecular clouds (MCs) within the SILCC-Zoom project. The MCs form in simulations of a 3-phase ISM which include its detailed chemical and dynamical evolution. First, I assess the reliability of polarisation observations from e.g. Planck and BlastPol. Next, discussing in detail the complex structure of MCs revealing both sheets and filaments, I will show how projection effects affect the observed orientation of magnetic fields. Furthermore, I will dicsuss the alignment efficiency of dust grains and show that polarisation observations of MCs mainly probe their dense parts up to AV > 1 (≥ 1000 cm-3). In addition, I combine my results with analytical considerations to shed light on the dynamical importance of magnetic fields. I will show that magnetic fields become perpendicular to (column) density structures above N = 1021-22 cm-2 and n ~ 1000 cm-3 and discuss how this orientation flip relates to the question where and when gravity starts to dominate over magnetic fields. This will give a holistic view of how magnetic fields affect both the dynamics and chemical evolution of molecular clouds. Finally, I will shed light on our latest results about which effects influence the wavelength dependence of the polarisation degree. Specifically, I will discuss the potential origin of V-shaped polarisation spectra in MCs. | |
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| Caption: The top panel shows the complicated gas structure inside MCs and how the fields lines become perpendicular to the dense, filamentary structures (blue). The lower left panel shows the effect of noise on the observed polarisation pattern. The lower right panel shows novel V-shaped polarisation spectra obtained within our work in combination to observations. | |
| Collaborators: S. Walch, U Köln, DE J. Soler, INAF , IT T. Balduin, TU Graz, AT |
Key publication
Relevant topic(s): Magnetic Fields Molecular Clouds |
| Relevant Big Question: What is the role of magnetic fields in MC evolution and how can we test it observationally? | |