Multiarm spirals on the periphery of disc galaxies

Spiral patterns in some disc galaxies have two arms in the centre, and three or more arms on the periphery. The same result is also obtained in numerical simulations of stellar and gaseous discs. We argue that such patterns may occur due to fast cooling of the gas, resulting in formation of giant mo...

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Bibliographic Details
Published in:arXiv.org 2018-01
Main Authors: Spiegel, Lubov, Polyachenko, Evgeny
Format: Article
Language:English
Subjects:
Computer simulation
Disk galaxies
Molecular clouds
Spirals
Stability
Online Access:Get full text
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Summary:Spiral patterns in some disc galaxies have two arms in the centre, and three or more arms on the periphery. The same result is also obtained in numerical simulations of stellar and gaseous discs. We argue that such patterns may occur due to fast cooling of the gas, resulting in formation of giant molecular clouds. The timescale of this process is 50 Myr, the factor of 10 shorter than of ordinary secular instability. The giant molecular clouds give rise to multiarm spirals through the mechanism of swing amplification.
ISSN:2331-8422