Magnetic fields as an alternative explanation for the rotation curves of spiral galaxies

Nature ◽  
1992 ◽  
Vol 360 (6405) ◽  
pp. 652-653 ◽  
Author(s):  
E. Battaner ◽  
J. L. Garrido ◽  
M. Membrado ◽  
E. Florido
Keyword(s):  
Magnetic Fields ◽  
Alternative Explanation ◽  
Spiral Galaxies ◽  
Rotation Curves

The Distribution of Radio Polarisation in Three Southern Galaxies

1991 ◽  
Vol 9 (2) ◽  
pp. 266-268
Author(s):  
J. I. Harnett ◽  
U. Klein ◽  
R. Wielebinski ◽  
R. F. Haynes
Keyword(s):  
Cosmic Rays ◽  
Magnetic Fields ◽  
Radio Telescope ◽  
Spiral Galaxies ◽  
Total Power ◽  
Transport Mechanisms ◽  
Contour Plots ◽  
Preliminary Study ◽  
Poloidal Magnetic Fields

AbstractWe are studying the distribution and morphology of magnetic fields in southern face-on and edge-on galaxies with the intention of clarifying the distribution, lifetimes and transport mechanisms of cosmic rays, and investigating the intensity and orientation of the disc, halo and poloidal magnetic fields. As a preliminary study, before the Australia Telescope was available, we observed a sample of well-known southern spiral galaxies with the Parkes radio telescope.Here, we present the resulting polarisation images for three galaxies, NGC 253, M 83 and NGC 4945, which were observed at 4.75 GHz and 8.55 GHz. The corresponding total power contour plots have been already published by Harnett et al. (1989a, 1990).

scholarly journals Magnetic Fields in Disks and Halos of Spiral Galaxies

1991 ◽  
Vol 144 ◽  
pp. 267-280 ◽  
Author(s):  
Rainer Beck
Keyword(s):  
Magnetic Fields ◽  
Large Scale ◽  
Spiral Galaxies ◽  
Coronal Holes ◽  
Azimuthal Angle ◽  
Total Strength ◽  
Radio Halo ◽  
Star Formation Activity ◽  
Energy Equipartition ◽  
Field Lines

Spiral galaxies host interstellar magnetic fields of 4-15 μG total strength. A significant fraction of the field lines shows large-scale structures. At face-on or moderately inclined view, the field lines run generally parallel to the spiral arms, either with uniform direction with respect to azimuthal angle (axisymmetric spiral, ASS), with one reversal along azimuthal angle (bisymmetric spiral, BSS), or with spiral orientation without dominating direction.At edge-on view, the field is concentrated in a thin disk, often surrounded by a thick radio disk with field lines mostly parallel to the plane, similar to the quadrupole-type dynamo field. Radio polarization data from NGC891 indicate that the thermal gas seen in Hα is responsible for Faraday depolarization. The required scaleheight of the field of ~4 kpc is comparable to the value expected in case of energy equipartition between magnetic fields and cosmic rays. The interacting edge-on galaxy NGC 4631 shows a much larger radio halo with field lines perpendicular to the disk, possibly driven by a strong galactic wind or the result of a dipole-type halo field.Field lines bending out of the plane are also visible in face-on galaxies as regions with high rotation measures and low star-formation activity. The resemblance to the phenomenon of the solar corona suggests to call them “galactic coronal holes”.

scholarly journals Rotation Curves in the Outer Parts of Galaxies from HI Observations

1978 ◽  
Vol 77 ◽  
pp. 23-31 ◽  
Author(s):  
Edwin E. Salpeter
Keyword(s):  
Spiral Galaxies ◽  
Rotation Curves ◽  
Flat Rotation Curves ◽  
Arecibo Observatory

21cm observations at the Arecibo Observatory for 9 edge-on spiral galaxies are described. Flat rotation curves are found in most cases.

scholarly journals Galactic Winds and Magnetic Fields from Spiral Galaxies

1990 ◽  
Vol 140 ◽  
pp. 177-181 ◽  
Author(s):  
H.J. Völk ◽  
D. Breitschwerdt ◽  
J.F. McKenzie
Keyword(s):  
Cosmic Rays ◽  
Magnetic Fields ◽  
Mass Loss ◽  
Magnetic Structure ◽  
Essential Role ◽  
Spiral Galaxies ◽  
High Energy ◽  
Energy Component ◽  
Galactic Winds ◽  
High Energy Component

Concentrating on our own Galaxy we discuss the dynamics of the outer halo, its magnetic structure and the occurrence of a supersonic mass loss in the form of a Galactic wind. The cosmic rays, as the nonthermal high energy component, de facto not influenced by gravity, play an essential role in the wind dynamics.

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