The Evolution of Galaxies

TL;DR

This paper reviews the complex processes driving galaxy evolution, including internal star formation, external gas accretion, galaxy mergers, and environmental interactions, highlighting their interplay and effects.

Contribution

It provides a comprehensive overview of internal and external mechanisms influencing galaxy evolution, emphasizing recent observational and theoretical insights.

Findings

Star formation is triggered internally or externally.

Gas accretion and merging significantly impact galaxy growth.

Environmental effects like ISM stripping influence galaxy evolution.

Abstract

The evolution of galaxies results from a combination of internal and external processes. The star formation is an internal process transforming cold and dense cores of molecular clouds to stars. It may be triggered internally by expanding shells, or externally, e. g. by galaxy collisions. The gas accretion and galaxy merging events are external contributors to galaxy evolution. They compete with another internal process of galaxy evolution, which is the secular evolution redistributing the mass and angular momentum inside of galaxies as a consequence of bar and spiral arms formation. As a nearby example of gas accretion we mention the interacting system Milky Way - Large and Small Magellanic Clouds. Stripping of ISM in galaxy clusters is reviewed as another example of interaction of galaxies with their environment.