A scenario that allows to estimate the net helicity of the galactic magnetic field is presented. Both magnetic helicity and baryon number are conserved during galaxy formation when the protogalactic cloud collapses. During this collapse, the helicity and baryon densities increase due to the decrease in the cloud volume, but the ratio of the helicity density to the baryon density remains unchanged. Hence the helicity density of the galactic magnetic field can be estimated to be ∼ -102nb, gal ∼ -10/cm3.
|Original language||English (US)|
|Journal||Physical Review Letters|
|State||Published - Dec 17 2001|
ASJC Scopus subject areas
- Physics and Astronomy(all)