Dynamical evolution of magnetic fields in the intracluster medium

Abstract

We investigate the evolution of magnetic fields in galaxy clusters starting from constant primordial fields using highly resolved ($\approx 4\mathrm{kpc}$) cosmological MHD simulations. The magnetic fields in our sample exhibit amplification via a small-scale dynamo and compression during structure formation. In particular, we study how the spectral properties of magnetic fields are affected by mergers, and we relate the measured magnetic energy spectra to the dynamical evolution of the intracluster medium. The magnetic energy grows by a factor of $\sim$ 40-50 in a time-span of $\sim 9$ Gyr and equipartition between kinetic and magnetic energy occurs on a range of scales ($<160\mathrm{kpc}$ at all epochs) depending on the turbulence state of the system. We also find that, in general, the outer scale of the magnetic field and the MHD scale are not simply correlated in time. The effect of major mergers is to shift the peak magnetic spectra to it smaller scales, whereas the magnetic amplification only starts after $\lesssim$ 1 Gyr. In contrast, continuous minor mergers promote the steady growth of the magnetic field. We discuss the implications of these findings in the interpretation of future radio observations of galaxy clusters.

Accepted in MNRAS; 16 pages, 34 figures

References in corpus (20)

• Turbulence and Magnetic Fields in the Large Scale Structure of the Universe
• Compressible Turbulence in Galaxy Clusters: Physics and Stochastic Particle Re-acceleration
• Current status of turbulent dynamo theory: From large-scale to small-scale dynamos
• Resolving the Formation of Protogalaxies. I. Virialization
• Cluster Magnetic Fields from Galactic Outflows
• Resolved magnetic dynamo action in the simulated intracluster medium
• Magnetohydrodynamic Simulations of Disk Galaxy Formation: the Magnetization of The Cold and Warm Medium
• Comparing Numerical Methods for Isothermal Magnetized Supersonic Turbulence
• On the amplification of magnetic fields in cosmic filaments and galaxy clusters
• The relation between gas density and velocity power spectra in galaxy clusters: high-resolution hydrodynamic simulations and the role of conduction
• Turbulence and Vorticity in Galaxy Clusters Generated by Structure Formation
• Hydrodynamical adaptive mesh refinement simulations of turbulent flows - II. Cosmological simulations of galaxy clusters
• Nonlinear growth of firehose and mirror fluctuations in turbulent galaxy-cluster plasmas
• Self-similar energetics in large clusters of galaxies
• Testing cosmic-ray acceleration with radio relics: a high-resolution study using MHD and tracers
• Large-Scale Structure Formation: from the first non-linear objects to massive galaxy clusters
• A small-scale dynamo in feedback-dominated galaxies - III. Cosmological simulations
• Origin of Magnetic Field in the Intracluster Medium: Primordial or Astrophysical?
• Features of collisionless turbulence in the intracluster medium from simulated Faraday rotation maps II: the effects of instabilities feedback
• Cluster magnetic fields through the study of polarized radio halos in the SKA era

Cited by in corpus (19)

• A radio ridge connecting two galaxy clusters in a filament of the cosmic web
• Second order Fermi reacceleration mechanisms and large scale synchrotron radio emission in intra-cluster bridges
• Fast magnetic field amplification in distant galaxyclusters
• The Coma cluster at LOFAR frequencies I: insights into particle acceleration mechanisms in the radio bridge
• Magnetic fields and relativistic electrons fill entire galaxy cluster
• Polarisation of Radio Relics in Galaxy Clusters
• Seed magnetic fields in turbulent small-scale dynamos
• The intra-cluster magnetic field in the double relic galaxy cluster Abell 2345
• Detecting shocked intergalactic gas with X-ray and radio observations
• Understanding the radio relic emission in the galaxy cluster MACS J0717.5+3745: spectral analysis
• The detection of cluster magnetic fields via radio source depolarisation
• Limiting the shock acceleration of cosmic-ray protons in the ICM
• Diffuse Radio Emission from Galaxy Clusters in the LOFAR Two-metre Sky Survey Deep Fields
• Connecting turbulent velocities and magnetic fields in galaxy cluster simulations with active galactic nuclei jets
• Turbulent magnetic fields in merging clusters: A case study of Abell 2146
• Evidence for strong intracluster magnetic fields in the early Universe
• Properties of Polarized Synchrotron Emission from Fluctuation Dynamo Action -- II. Effects of Turbulence Driving in the ICM and Beam Smoothing
• How complex is the cosmic web?
• Saturation mechanism of the fluctuation dynamo in supersonic turbulent plasmas