Sub-Alfvenic Non-Ideal MHD Turbulence Simulations with Ambipolar Diffusion: III. Implications for Observations and Turbulent Enhancement

Abstract

Ambipolar diffusion (AD) is believed to be a crucial process for redistributing magnetic flux in the dense molecular gas that occurs in regions of star formation. We carry out numerical simulations of this process in regions of low ionization using the heavy ion approximation. The simulations are for regions of strong field (plasma β=0.1) and mildly supersonic turbulence (M=3, corresponding to an Alfven mach number of 0.67). The velocity power spectrum of the neutral gas changes from an Iroshnikov-Kraichnan spectrum in the case of ideal MHD to a Burgers spectrum in the case of a shock-dominated hydrodynamic system. The magnetic power spectrum shows a similar behavior. We use a 1D radiative transfer code to post-process our simulation results; the simulated emission from the CS J=2-1 and H13CO+ J=1-0 lines shows that the effects of AD are observable in principle. Linewidths of ions are observed to be less than those of neutrals, and we confirm previous suggestions that this is due to AD. We show that AD is unlikely to affect the Chandrasekhar-Fermi method for inferring field strengths unless the AD is stronger than generally observed. Finally, we present the first fully 3D study of the enhancement of AD by turbulence, finding that AD is accelerated by factor 2-4.5 for non self-gravitating systems with the level of turbulence we consider.

22 pages, 8 figures

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Cited by in corpus (12)

• Magnetized Interstellar Molecular Clouds. I. Comparison Between Simulations and Zeeman Observations
• Magnetized interstellar molecular clouds: II. The Large-Scale Structure and Dynamics of Filamentary Molecular Clouds
• Ambipolar Diffusion Heating in Turbulent Systems
• Turbulent energy dissipation and intermittency in ambipolar diffusion magnetohydrodynamics
• Gravitational instability of filamentary molecular clouds, including ambipolar diffusion
• The Magnetized Environment of the W3(H2O) Protostars
• Probing the Turbulence Dissipation Range and Magnetic Field Strengths in Molecular Clouds. II. Directly Probing the Ion-neutral Decoupling Scale
• Probing the Turbulent Ambipolar Diffusion Scale in Molecular Clouds with Spectroscopy
• Ambipolar diffusion regulated collapse of filaments threaded by perpendicular magnetic fields
• Analytic characterization of sub-Alfvénic turbulence energetics
• Magnetic Fields and Star Formation
• CO Structures with Narrow Lines in Nearby Quiescent Regions