Stealth magnetic field in de Sitter spacetime

TL;DR

This paper discovers a stable de Sitter universe solution with a homogeneous magnetic field in a non-minimally coupled scalar-tensor gravity model, considering backreaction effects and potential implications for early universe magnetogenesis.

Contribution

It introduces a novel cosmological attractor solution featuring a magnetic field in de Sitter space within a specific gauge theory framework, accounting for backreaction and symmetry considerations.

Findings

Stable de Sitter solution with magnetic field found

Solution includes backreaction of magnetic field on geometry

Deformation leads to Bianchi type-I universe with magnetic and electric fields

Abstract

In the context of a U(1) gauge theory non-minimally coupled to scalar-tensor gravity, we find a cosmological attractor solution that represents a de Sitter universe with a homogeneous magnetic field. The solution fully takes into account backreaction of the magnetic field to the geometry and the scalar field. Such a solution is made possible by scaling-type global symmetry and fine-tuning of two parameters of the theory. If the fine-tuning is relaxed then the solution is deformed to an axisymmetric Bianchi type-I universe with constant curvature invariants, a homogeneous magnetic field and a homogeneous electric field. Implications to inflationary magnetogenesis are briefly discussed.