Flat rotation curves, inverse cascade, and magnetic fields

We critically examine the recently suggested alternatives to dark matter in spiral galaxies. We look into the inverse cascade in turbulent galactic disks and the magnetic alternative. We conclude that some amount of dark matter is necessary on galactic scales. However, we speculate the possibility that the constancy of the H I-dark matter ratio may have a magnetohydrodynamic explanation. © 1996. The American Astronomical Society.