Turbulence generated by large-scale motions during structure formation affects the evolution of the thermal and non-thermal components of the intracluster medium. As enstrophy is a measure of the magnitude of vorticity, we study the generation and evolution of turbulence by analysing the Lagrangian history of enstrophy. For this purpose, we combine cosmological simulations carried out with the ENZO code with our Lagrangian post-processing tool CRATER. This way we are able to quantify the individual source terms of enstrophy in the course of the accretion of groups on to galaxy clusters. Here, we focus on the redshift range from z = 1 to z = 0. Finally, we measure the rate of dissipation of turbulence and estimate the resulting amplification of intracluster magnetic fields.We find that compressive and baroclinic motions are the main sources of enstrophy, while stretching motions and dissipation affect most of the ensuing enstrophy evolution. The rate of turbulent dissipation is able to sustain the amplification of intracluster magnetic fields to observed levels.
Bibliographical noteFunding Information:
We thankfully acknowledge G. Brunetti and D. Eckert for fruitful scientific conversations.DWacknowledges support by the Deutsche Forschungsgemeinschaft (DFG) through grants SFB 676 and BR 2026/17. TWJ acknowledges support from the US NSF through grant AST121159. FV acknowledges personal support from the grant VA 876/3-1 from the DFG, and from the European Union's Horizon 2020 research and innovation programme under the Marie-Sklodowska-Curie grant agreement no. 664931. FV and MB also acknowledge partial support from the grant FOR1254 from DFG. The ENZO-simulations have been carried out in the ITASCA-cluster hosted by the University of Minnesota
© 2017 The Authors.
- Galaxies: clusters: intracluster medium
- Magnetic fields