PITCH ANGLE OF GALACTIC SPIRAL ARMS

One of the key parameters that characterizes spiral arms in disk galaxies is a pitch angle that measures the inclination of a spiral arm to the direction of galactic rotation. The pitch angle differs from galaxy to galaxy, which suggests that the rotation law of galactic disks determines it. In orde...

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Bibliographic Details
Published in:The Astrophysical journal 2014-06, Vol.787 (2), p.1-7, Article 174
Main Authors: MICHIKOSHI, SHUGO, Kokubo, Eiichiro
Format: Article
Language:English
Subjects:
AMPLIFICATION
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COMPUTERIZED SIMULATION
Differential rotation
Disk galaxies
Dynamical systems
Galactic rotation
Galactic structure
GALAXIES
INCLINATION
MANY-BODY PROBLEM
Pitch angle
ROTATION
Shear rate
SPIRAL CONFIGURATION
STARS
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Summary:One of the key parameters that characterizes spiral arms in disk galaxies is a pitch angle that measures the inclination of a spiral arm to the direction of galactic rotation. The pitch angle differs from galaxy to galaxy, which suggests that the rotation law of galactic disks determines it. In order to investigate the relation between the pitch angle of spiral arms and the shear rate of galactic differential rotation, we perform local N-body simulations of pure stellar disks. We find that the pitch angle increases with the epicycle frequency and decreases with the shear rate and obtain the fitting formula. This dependence is explained by the swing amplification mechanism.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/787/2/174