Magnetic fields in the interstellar medium

Magnetic fields are everywhere in the interstellar medium and are locally strong enough to modify the dynamics. Diffuse warm gas in the ISM is very likely to be supported by magnetic pressure. In dense, star forming regions the magnetic fields can be very strong such that the gas flow is channeld by the field structure. Using three-dimensional magneto-hydrodynamical simulations we study the impact of magnetic fields on the ISM, in particular the transition from diffuse warm atomic to dense colde molecular gas. In addition, we investigate the oriantation of the magnetic field compared to the orientation of the gas structures and the gas flows.

I published two papers related to the magnetic fields in the ISM (the first is linked the second will be there soon):

• Girichidis et al. (2018) MNRAS 480, 3511G

The following video shows the total column density of a fraction of the galactic disc egde-on (top) and face-on (bottom) for three different magnetic fields; no field (left-hand panels), a 3μG field (middle panel), and a 6μG field (right-hand panel).

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There are two main differences between the simulations. The first is that the runs including magnetic fields have smaller density contrasts. The dense gas is embedded in larger cloud complexes rather than in locally isolated clouds. The second is that dense gas forms later because the additional magnetic pressure supports the gas against fast compression and the resulting faster cooling. This can be nicely seen in the formation of molecular gas here:

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