Pitch angle of galactic spiral arms

Journal Article · Sun Jun 01 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/787/2/174· OSTI ID:22356742

Michikoshi, Shugo ^[1]; Kokubo, Eiichiro ^[2]

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1. Department of Environmental Systems Science, Doshisha University, Tatara Miyakodani 1-3, Kyotanabe City, Kyoto 610-0394 (Japan)
2. Division of Theoretical Astronomy, National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan)

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.

• OSTI ID: 22356742
• Journal Information: Astrophysical Journal, Vol. 787, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
AMPLIFICATION
COMPUTERIZED SIMULATION
GALAXIES
INCLINATION
MANY-BODY PROBLEM
ROTATION
SPIRAL CONFIGURATION
STARS