Primordial Magnetic Fields From String Cosmology

TL;DR

This paper proposes a mechanism within string cosmology where primordial magnetic fields are generated from amplified electromagnetic vacuum fluctuations during a dilaton-driven inflationary epoch, potentially explaining observed intergalactic magnetic fields.

Contribution

It introduces a novel scenario in string cosmology that naturally produces seed magnetic fields through vacuum fluctuation amplification during pre-big-bang inflation.

Findings

Primordial magnetic seeds can emerge from string cosmology models.

Amplification depends on the duration of the stringy era and the dynamics of the dilaton.

The mechanism aligns with observed intergalactic magnetic fields.

Abstract

Sufficiently large seeds for generating the observed (inter)galactic magnetic fields emerge naturally in string cosmology from the amplification of electromagnetic vacuum fluctuations due to a dynamical dilaton background. The success of the mechanism depends crucially on two features of the so-called pre-big-bang scenario, an early epoch of dilaton-driven inflation at very small coupling, and a sufficiently long intermediate stringy era preceding the standard radiation-dominated evolution.