Astrophysics > Cosmology and Nongalactic Astrophysics
[Submitted on 25 Nov 2024]
Title:Non-linear saturation and energy transport in global simulations of magneto-thermal turbulence in the stratified intracluster medium
View PDF HTML (experimental)Abstract:Context. The magneto-thermal instability (MTI) is one of many possible drivers of stratified turbulence in the intracluster medium (ICM) outskirts of galaxy clusters, where the background temperature gradient is aligned with the gravity. This instability occurs because of the fast anisotropic conduction of heat along magnetic field lines; but to what extent it impacts the ICM dynamics, energetics and overall equilibrium is still a matter of debate. Aims. This work aims at understanding MTI turbulence in an astrophysically stratified ICM atmosphere, its saturation mechanism, and its ability to carry energy and to provide non-thermal pressure support. Methods. We perform a series of 2D and 3D numerical simulations of the MTI in global spherical models of stratified ICM, thanks to the finite-volume code IDEFIX, using Braginskii-magnetohydrodynamics. We use volume-, shell-averaged and spectral diagnostics to study the saturation mechanism of the MTI, and its radial transport energy budget. Results. The MTI is found to saturate through a dominant balance between injection and dissipation of available potential energy, which amounts to marginalising the Braginskii heat flux but not the background temperature gradient itself. Accordingly, the strength and injection length of MTI-driven turbulence exhibit clear dependencies on the thermal diffusivity. The MTI drives cluster-size motions with Mach numbers up to $\mathcal{M} \sim 0.3$, even in presence of strong stable entropy stratification. We show that such mildly compressible flows can provide about $\sim 15\%$ of non-thermal pressure support in the outermost ICM regions, and that the convective transport itself is much less efficient than conduction at radially transporting energy. Finally, we show that the MTI saturation can be described by a diffusive mixing-length theory, shedding light on the diffusive buoyant nature of the instability.
Current browse context:
astro-ph.CO
Change to browse by:
References & Citations
Bibliographic and Citation Tools
Bibliographic Explorer (What is the Explorer?)
Connected Papers (What is Connected Papers?)
Litmaps (What is Litmaps?)
scite Smart Citations (What are Smart Citations?)
Code, Data and Media Associated with this Article
alphaXiv (What is alphaXiv?)
CatalyzeX Code Finder for Papers (What is CatalyzeX?)
DagsHub (What is DagsHub?)
Gotit.pub (What is GotitPub?)
Hugging Face (What is Huggingface?)
Papers with Code (What is Papers with Code?)
ScienceCast (What is ScienceCast?)
Demos
Recommenders and Search Tools
Influence Flower (What are Influence Flowers?)
CORE Recommender (What is CORE?)
IArxiv Recommender
(What is IArxiv?)
arXivLabs: experimental projects with community collaborators
arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website.
Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them.
Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs.