2009ApJ...706L.155H -
Astrophys. J., 706, L155-L159 (2009/November-3)
Global galactic dynamo driven by cosmic rays and exploding magnetized stars.
HANASZ M., WOLTANSKI D. and KOWALIK K.
Abstract (from CDS):
We report the first results of the first global galactic-scale cosmic ray (CR)-MHD simulations of CR-driven dynamo. We investigate the dynamics of magnetized interstellar medium (ISM), which is dynamically coupled with CR gas. We assume that exploding stars deposit small-scale, randomly oriented, dipolar magnetic fields into the differentially rotating ISM, together with a portion of CRs, accelerated in supernova shocks. We conduct numerical simulations with the aid of a new parallel MHD code PIERNIK. We find that the initial magnetization of galactic disks by exploding magnetized stars forms favorable conditions for the CR-driven dynamo. We demonstrate that dipolar magnetic fields supplied on small supernova remnant scales can be amplified exponentially by the CR-driven dynamo, to the present equipartition values, and transformed simultaneously to large galactic scales. The resulting magnetic field structure in an evolved galaxy appears spiral in the face-on view and reveals the so-called X-shaped structure in the edge-on view.
Abstract Copyright:
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Journal keyword(s):
cosmic rays - galaxies: ISM - galaxies: magnetic fields - ISM: magnetic fields - MHD
Simbad objects:
2
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