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Magnetic spiral arms and galactic outflows

Lookup NU author(s): Dr Luke Chamandy, Professor Anvar ShukurovORCiD

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Abstract

Galactic magnetic arms have been observed between the gaseous arms of some spiral galaxies; their origin remains unclear. We suggest that magnetic spiral arms can be naturally generated in the interarm regions because the galactic fountain flow or wind is likely to be weaker there than in the arms. Galactic outflows lead to two countervailing effects: removal of small-scale magnetic helicity, which helps to avert catastrophic quenching of the dynamo, and advection of the large-scale magnetic field, which suppresses dynamo action. For realistic galactic parameters, the net consequence of outflows being stronger in the gaseous arms is higher saturation large-scale field strengths in the interarm regions as compared to in the arms. By incorporating rather realistic models of spiral structure and evolution into our dynamo models, an interlaced pattern of magnetic and gaseous arms can be produced.

Publication metadata

Author(s): Chamandy L, Shukurov A, Subramanian K

Publication type: Article

Publication status: Published

Journal: Monthly Notices Letters of the Royal Astronomical Society

Year: 2015

Volume: 446

Issue: 1

Pages: L6-L10

Print publication date: 01/01/2015

Online publication date: 17/10/2014

Acceptance date: 16/09/2014

ISSN (print): 0035-8711

ISSN (electronic): 1365-2966

Publisher: Oxford University Press

URL: http://dx.doi.org/10.1093/mnrasl/slu156

DOI: 10.1093/mnrasl/slu156

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