A numerical study of primordial magnetic field amplification by inflation-produced gravitational waves

TL;DR

This study numerically investigates the interaction between inflation-produced magnetic fields and gravitational waves, confirming that gravitational waves have a negligible effect on amplifying primordial magnetic fields during inflation.

Contribution

It provides a detailed numerical analysis of magnetic field and gravitational wave interactions, clarifying the limited role of gravitational waves in primordial magnetic field amplification.

Findings

Gravitational waves have a minimal impact on magnetic field amplification.

Numerical results support analytical predictions of weak influence.

The study considers magnetohydrodynamic effects and Alfven speed variations.

Abstract

We numerically study the interaction of inflation-produced magnetic fields with gravitational waves, both of which originate from quantum fluctuations during inflation. The resonance between the magnetic field perturbations and the gravitational waves has been suggested as a possible mechanism for magnetic field amplification. However, some analytical studies suggest that the effect of the inflationary gravitational waves is too small to provide significant amplification. Our numerical study shows more clearly how the interaction affects the magnetic fields and confirms the weakness of the influence of the gravitational waves. We present an investigation based on the magnetohydrodynamic approximation and take into account the differences of the Alfven speed.