Modeling the Galactic Center Nonthermal Filaments as Magnetized Wakes

Russell B. Dahlburg
Laboratory for Computational Physics and Fluid Dynamics, Naval Research Laboratory, Washington, DC 20375-5344; rdahlbur@lcp.nrl.navy.mil
Giorgio Einaudi
Dipartimento di Fisica e Istituto Nazionale Fisica Materia, Sez. A, Università di Pisa, 56100 Pisa, Italy; einaudi@df.unipi.it
T. N. LaRosa
Department of Biological and Physical Sciences, Kennesaw State University, 1000 Chastain Road, Kennesaw, GA 30144; ted@avatar.kennesaw.edu
and
Steven N. Shore
Department of Physics and Astronomy, Indiana University South Bend, 1700 Mishawaka Avenue, South Bend, IN 46634-7111; sshore@paladin.iusb.edu

Received 2001 September 17; accepted 2001 November 26

ABSTRACT

We simulate the Galactic center nonthermal filaments as magnetized wakes formed dynamically from amplification of a weak (tens of micro Gauss) global magnetic field through the interaction of molecular clouds with a Galactic center wind. One of the key issues in this cometary model is the stability of the filament against dynamical disruption. Here we show two-dimensional MHD simulations for interstellar conditions that are appropriate for the Galactic center. The structures eventually disrupt through a shear-driven nonlinear instability but maintain coherence for lengths up to 100 times their width as observed. The final instability, which destroys the filament through shredding and plasmoid formation, grows quickly in space (and time) and leads to an abrupt end to the structure, in accord with observations. As a by-product, the simulation shows that emission should peak well downstream from the cloud-wind interaction site.