Helical intergalactic magnetic fields at the ∼10-14 G level on ∼10 Mpc length scales are indicated by current gamma ray observations. The existence of magnetic fields in cosmic voids and their nontrivial helicity suggest that they must have originated in the early Universe and thus have implications for the fundamental interactions. We derive the spectrum of the cosmological magnetic field as implied by observations and MHD evolution, yielding order nano Gauss fields on kiloparsec scales and a "large helicity puzzle" that needs to be resolved by the fundamental interactions. The importance of CP violation and a possible crucial role for chiral effects or axions in the early Universe are pointed out.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)