2009/03/22 by Xiaoyue Guan, Charles F. Gammie · 4 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #astro-ph.GA #astro-ph.HE
paper · pdf · doi:10.1088/0004-637x/697/2/1901
published as Astrophys.J.697:1901-1906,2009 · 15pages, 1 figure, accepted by ApJ
arxiv created 2009/03/22 · openalex publication_date 2009/05/15 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
The magnetic Prandtl number Pr M is the ratio of viscosity to resistivity. In astrophysical disks the diffusion of angular momentum (viscosity) and magnetic fields (resistivity) are controlled by turbulence. Phenomenological models of the evolution of large-scale poloidal magnetic fields in disks suggest that the turbulent magnetic Prandtl number Pr M,T controls the rate of escape of vertical field from the disk; for Pr M,T ⩽ R / H vertical field diffuses outward before it can be advected inward by accretion. Here we measure field diffusion and angular momentum transport due to MHD turbulence in a shearing box, and thus Pr M,T , by studying the evolution of a sinusoidal perturbation in the magnetic field that is injected into a turbulent background. We show that the perturbation is always stable, decays approximately exponentially, has decay rate ∝ k 2 , and that the implied Pr M,T ∼ 1.