Inflationary and phase-transitional primordial magnetic fields in galaxy clusters

TL;DR

This study uses high-resolution simulations to compare how inflationary and phase transition primordial magnetic fields evolve in galaxy clusters, revealing distinct spectral and strength differences that can inform future observational tests.

Contribution

It provides the first detailed simulation-based comparison of inflationary and phase transition PMFs in galaxy clusters, highlighting their distinct amplification and spectral characteristics.

Findings

Inflationary PMFs are more efficiently amplified by turbulence.

Final magnetic field strengths differ by an order of magnitude.

Spectral features encode information about the origin of PMFs.

Abstract

Primordial magnetic fields (PMFs) are possible candidates for explaining the observed magnetic fields in galaxy clusters. Two competing scenarios of primordial magnetogenesis have been discussed in the literature: inflationary and phase-transitional. We study the amplification of both large- and small-scale correlated magnetic fields, corresponding to inflation- and phase transition-generated PMFs, in a massive galaxy cluster. We employ high-resolution magnetohydrodynamic cosmological zoom-in simulations to resolve the turbulent motions in the intracluster medium. We find that the turbulent amplification is more efficient for the large-scale inflationary models, while the phase transition-generated seed fields show moderate growth. The differences between the models are imprinted on the spectral characteristics of the field (such as the amplitude and the shape of the magnetic power spectrum) and therefore on the final correlation length. We find a one order of magnitude difference between the final strengths of the inflation- and phase transition-generated magnetic fields, and a factor of 1.5 difference between their final coherence scales. Thus, the final configuration of the magnetic field retains information about the PMF generation scenarios. Our findings have implications for future extragalactic Faraday rotation surveys with the possibility of distinguishing between different magnetogenesis scenarios.