Picogauss magnetic fields in voids from ultra-high energy cosmic rays

TL;DR

This paper proposes that ultra-high energy cosmic rays from galaxy clusters can generate magnetic fields in cosmic voids, reaching observable magnitudes without primordial origins, aligning with current observational bounds.

Contribution

It introduces a novel mechanism linking cosmic rays to magnetic field generation in voids, explaining observed field strengths without primordial assumptions.

Findings

Magnetic fields in voids can reach ~10^-12 G

Coherence lengths of magnetic fields can be tens of Mpc

The mechanism aligns with observational bounds

Abstract

We argue that ultra-high energy cosmic rays emitted by galaxy clusters result in electric currents in filaments of the large-scale structure that are sufficient to generate magnetic fields in voids of the magnitude of ~1e-12 G and the coherence length of up to tens of Mpc. These fields satisfy both the lower and upper observational bounds on magnetic fields in voids without a need of any primordial component.