Dynamics of Disks and Warps

TL;DR

This chapter reviews the theoretical understanding of galaxy disk dynamics, including instabilities, warps, bars, spiral patterns, and star scattering, highlighting current knowledge and unresolved questions.

Contribution

It synthesizes existing theories on galaxy disk instabilities, warps, and bars, and discusses recent developments and open questions in the field.

Findings

Identified all known collective global instabilities in galaxy disks.

Discussed mechanisms of warps and bending waves in detail.

Highlighted unresolved issues regarding the origin and frequency of galactic bars.

Abstract

This chapter reviews theoretical work on the stellar dynamics of galaxy disks. All the known collective global instabilities are identified, and their mechanisms described in terms of local wave mechanics. A detailed discussion of warps and other bending waves is also given. The structure of bars in galaxies, and their effect on galaxy evolution, is now reasonably well understood, but there is still no convincing explanation for their origin and frequency. Spiral patterns have long presented a special challenge, and ideas and recent developments are reviewed. Other topics include scattering of disk stars and the survival of thin disks.