Magnetic Fields in Multiphase Turbulence: Impacts on Dynamics and Structure

TL;DR

This study investigates how magnetic fields influence the mixing, growth, and morphology of multiphase gas in turbulent astrophysical environments, revealing that magnetic fields generally suppress mixing but have limited impact on cold gas survival and structure.

Contribution

It provides a comparative analysis of magnetic effects on multiphase turbulence using TRML and box simulations, clarifying their influence on mixing and gas morphology.

Findings

Magnetic fields suppress mixing in TRMLs but have marginal effects in turbulent box simulations.

Cold gas clump size distribution is unaffected by magnetic fields, but clumps are more filamentary with magnetic fields.

Synthetic MgII absorption lines are similar with or without magnetic fields, matching observations.

Abstract

Both multiphase gas and magnetic fields are ubiquitous in astrophysics. However, the influence of magnetic fields on mixing of the different phases is still largely unexplored. In this study, we use both turbulent radiative mixing layer (TRML) and turbulent box simulations to examine the effects of magnetic fields on cold gas growth rates, survival, and the morphology of the multiphase gas. Our findings indicate that, in general, magnetic fields suppress mixing in TRMLs while turbulent box simulations show comparatively marginal differences in growth rates and survival of the cold gas. We reconcile these two seemingly contrasting results by demonstrating that similar turbulent properties result in comparable mixing -- regardless of the presence or absence of magnetic fields. We, furthermore, find the cold gas clump size distribution to be independent of the magnetic fields but the clumps are more filamentary in the MHD case. Synthetic MgII absorption lines support this picture being marginally different with and without magnetic fields; both cases aligning well with observations. We also examine the magnetic field strength and structure in turbulent boxes. We generally observe a higher mean magnetic field in the cold gas phase due to flux freezing and reveal fractal-like magnetic field lines in a turbulent environment.