Cosmological electromagnetic fields and dark energy

TL;DR

This paper proposes that a cosmological-scale electromagnetic field, originating from quantum fluctuations during inflation, can naturally produce an effective cosmological constant explaining dark energy without new physics.

Contribution

It introduces a model where primordial electromagnetic fluctuations generate a dark energy component, linking inflationary physics to the current accelerated expansion.

Findings

Electromagnetic fields on cosmological scales can mimic a cosmological constant.

The model aligns with local gravity tests and remains stable.

Upcoming observations could distinguish this mechanism from a true cosmological constant.

Abstract

We show that the presence of a temporal electromagnetic field on cosmological scales generates an effective cosmological constant which can account for the accelerated expansion of the universe. Primordial electromagnetic quantum fluctuations produced during electroweak scale inflation could naturally explain the presence of this field and also the measured value of the dark energy density. The behavior of the electromagnetic field on cosmological scales is found to differ from the well studied short-distance behavior and, in fact, the presence of a non-vanishing cosmological constant could be signalling the breakdown of gauge invariance on cosmological scales. The theory is compatible with all the local gravity tests, and is free from classical or quantum instabilities. Thus we see that, not only the true nature of dark energy can be established without resorting to new physics, but also the value of the cosmological constant finds a natural explanation in the context of standard inflationary cosmology. This mechanism could be discriminated from a true cosmological constant by upcoming observations of CMB anisotropies and large scale structure.