# Constraints on the production of primordial magnetic seeds in pre-big bang cosmology

## TL;DR

This paper investigates how certain string cosmology models can produce primordial magnetic seeds compatible with observations, and finds a parameter space where these seeds and detectable gravitational waves coexist.

## Contribution

It identifies a specific parameter space in string cosmology models that allows for both magnetic seed production and detectable relic gravitational waves.

## Key findings

- Efficient magnetic seed production is possible within a restricted parameter space.
- This parameter space overlaps with regions predicting detectable gravitational waves.
- Models can simultaneously explain magnetic seeds and gravitational wave signals.

## Abstract

We study the amplification of the electromagnetic fluctuations, and the production of "seeds" for the cosmic magnetic fields, in a class of string cosmology models whose scalar and tensor perturbations reproduce current observations and satisfy known phenomenological constraints. We find that the condition of efficient seeds production can be satisfied and compatible with all constraints only in a restricted region of parameter space, but we show that such a region has significant intersections with the portions of parameter space where the produced background of relic gravitational waves is strong enough to be detectable by aLIGO/Virgo and/or by eLISA.