Origin of Primordial Magnetic Fields

Determine the physical origin of primordial magnetic fields in the early Universe and identify a viable mechanism that accounts for their observed manifestations in galaxies, galaxy clusters, and intergalactic space.

Background

The paper begins by situating its non-singular ekpyrotic-bounce magnetogenesis scenario within the broader cosmological problem of explaining primordial magnetic fields. Magnetic fields are observed in galaxies and galaxy clusters, and intergalactic magnetic-field constraints motivate mechanisms capable of generating them in the early Universe. Standard Maxwell electrodynamics is conformally invariant in a conformally flat FLRW spacetime, so electromagnetic vacuum fluctuations are not amplified solely by cosmic expansion. The paper investigates whether a time-dependent scalar–electromagnetic coupling during ekpyrotic contraction can provide such an amplification mechanism, but the general origin of primordial magnetic fields remains unresolved.