Are rotation curves in NGC 6946 and the Milky Way magnetically supported?
Following the model of magnetically supported rotation of spiral galaxies, the inner disk rotation is dominated by gravity but magnetism is not negligible at radii where the rotation curve becomes flat, and indeed becomes dominant at very large radii. Values of the order of 1 $\mu$G, or even less, p...
Saved in:
Main Authors | , |
---|---|
Format | Journal Article |
Language | English |
Published |
30.03.2005
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Following the model of magnetically supported rotation of spiral galaxies,
the inner disk rotation is dominated by gravity but magnetism is not negligible
at radii where the rotation curve becomes flat, and indeed becomes dominant at
very large radii. Values of the order of 1 $\mu$G, or even less, produce a
centripetal force when the absolute value of the slope of the curve [$B_\phi$,
R] (azimuthal field strength versus radius) is less than $R^{-1}$. The
$R^{-1}$-profile is called the critical profile. From this hypothesis, the
following is to be expected: at large radii, a ``subcritical'' profile (slope
flatter than $R^{-1}$); at still larger radii a $B_\phi$-profile becoming
asymptotically critical as the density becomes asymptotically vanishing. Recent
observations of magnetic fields in NGC 6946 and the Milky Way are in very good
agreement with these predictions. This magnetic alternative requires neither
galactic dark matter (DM) nor modification of fundamental laws of physics, but
it is not in conflict with these hypotheses, especially with the existence of
cosmological cold dark matter (CDM). |
---|---|
DOI: | 10.48550/arxiv.astro-ph/0503657 |