Joanna Jałocha, Łukasz Bratek, Jan Pȩkala, Marek Kutschera
We address the problem of the influence of large-scale magnetic fields on
galactic rotation on the example of spiral galaxy NGC 891. Based on its
rotation curve and the surface density of HI we determine, in the framework of
the global disk model, the surface density of matter. Then, based on the
surface brightness, we determine the corresponding profile of local
mass-to-light ratio. We model also the vertical gradient of azimuthal velocity
in the quasi-circular orbits approximation, and we compare it with
measurements. We discuss what factors may influence the rotation of matter in
NGC 891 and how this can translate to changes in the profile of local
mass-to-light ratio. In particular, we discuss a possible effect of magnetic
fields on the motion of ionized gas, and consequently, on the determination of
the profile of local mass-to-light ratio. Finally, we put forward the
hypothesis, that the asymmetry in magnetic fields observed in NGC 891 might be
responsible for the anomalous behaviour of the vertical gradient of rotation
observed in NGC 891.
View original:
http://arxiv.org/abs/1111.6417
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