Dependence of the fluctuation dynamo on cluster assembly history

Clarify how the small-scale fluctuation dynamo depends on the assembly history of galaxy clusters and establish a fuller understanding of the dynamo process itself.

Background

The paper discusses the amplification of intracluster magnetic fields by velocity fluctuations through stretching and folding of magnetic field lines, which promotes a small-scale fluctuation dynamo. Although cosmological magnetohydrodynamic simulations provide evidence for such amplification, the physical dynamo mechanism and its dependence on the cluster’s assembly history are not yet fully understood. The authors identify resolving this dependence and clarifying the mechanism as a central unresolved problem motivating further theoretical work.

References

These velocity fluctuations amplify the ICM magnetic field by stretching and folding magnetic field lines and promoting a small-scale (turbulent or fluctuation) dynamo, a mechanism that remains not fully understood even in controlled numerical experiments \citep[e.g.][]{Schekochihin02,Schekochihin04,Rincon19}. Establishing how it depends on the assembly history, as well as clarifying the dynamo process itself, remains a key open problem.

— Monitoring the power spectrum of magnetic field fluctuations across the simulated intracluster medium  (2609.19307 - Bartalesi et al., 16 Sep 2026) in Section 1, Introduction