Excitation of Photons by Inflationary Gravitons

TL;DR

This paper investigates how inflationary gravitons can excite photons during cosmic inflation, leading to a secular increase in electric fields that could seed primordial magnetic fields.

Contribution

It provides a novel calculation of photon excitation due to gravitons during inflation using one-loop vacuum polarization on de Sitter space.

Findings

Electric field experiences secular enhancement proportional to inflationary e-foldings.

Establishes a minimum inflation duration needed to seed cosmic magnetic fields.

Demonstrates the impact of gravitons on photon dynamics during inflation.

Abstract

We use a recent result for the graviton contribution to the one loop vacuum polarization to solve the effective field equations for dynamical photons on de Sitter background. Our results show that the electric field experiences a secular enhancement proportional to the number of inflationary e-foldings. We discuss the minimum this establishes for primordial inflation to seed cosmic magnetic fields.