Speaker
Description
Magnetic fields can play an important role in the energy balance and formation of gas structures in galaxies. However, their dynamical effect on the rotation curve of galaxies is immensely unexplored. We investigate the dynamical impact of the known magnetic arms of NGC 6946 on its circular gas rotation traced in HI, considering two dark-matter mass-density models, ISO, and the universal NFW profile.
By simulating the galactic magnetic field structure in three dimensions and using the magnetohydrodynamics (MHD) equation of motion for the fluid dynamics, we found that the contribution ratio of the regular magnetic field to the observed circular velocity and to the dark matter increases with the galactocentric radius.
The shape of the H I gas rotation curve is reproduced better, including the magnetic field's effect, especially in the outer part, where the dynamical effect of the magnetic field could become important. Therefore, the large-scale magnetic fields cannot be completely ignored in the large-scale dynamics of spiral galaxies, especially in the outer parts of galaxies.
