Inflationary Magnetogenesis without the Strong Coupling Problem II: Constraints from CMB anisotropies and B-modes

Understand

Recent observational claims of magnetic fields stronger than $10^{-16}$ G in the extragalactic medium motivate a new look for their origin in the inflationary magnetogenesis models.

• In this work we shall review the constraints on the simplest gauge invariant model $f^2(\phi)F_{\mu \nu}F^{\mu \nu}$ of inflationary magnetogenesis, and show that in the optimal region of parameter space the anisotropic constraints coming from the induced bispectrum, due to the generated electromagnetic fields, yield the strongest constraints.
• In this model, only a very fine tuned scenario at an energy scale of inflation as low as $10^{-2}$ GeV can explain the observations of void magnetic fields.
• These findings are consistent with the recently derived model independent constraints.