Fundamental Implications of Intergalactic Magnetic Field Observations

TL;DR

This paper discusses the implications of observed helical intergalactic magnetic fields for early universe physics, highlighting their potential origins and the role of fundamental interactions like CP violation.

Contribution

It combines observational data and cosmological magnetic field dynamics to identify key characteristics that any generation mechanism must explain, emphasizing early universe processes.

Findings

Magnetic fields of ~10^{-14} G on 10 Mpc scales are observed.

Helicity and void presence suggest an early universe origin.

CP violation and chiral effects are crucial in magnetic field generation.

Abstract

Helical intergalactic magnetic fields at the $\sim 10^{-14}~{\rm G}$ level on $\sim 10~{\rm Mpc}$ length scales are indicated by current gamma ray observations. The existence of magnetic fields in cosmic voids and their non-trivial helicity suggest that they must have originated in the early universe and thus have implications for the fundamental interactions. I combine present knowledge of the observational constraints and the dynamics of cosmological magnetic fields to derive characteristics that would need to be explained by the magnetic field generation mechanism. The importance of CP violation and a possible crucial role for chiral effects in the early universe are pointed out.