# The Impact of Stellar Migration on Disk Outskirts

## TL;DR

This paper reviews how stellar migration mechanisms like churning and scattering influence the structure of galaxy outer disks, highlighting their roles in different galaxy profile types and suggesting future research directions.

## Contribution

It provides a review and analysis of stellar migration effects on galaxy outer disks, linking migration types to galaxy profile classifications.

## Key findings

- Churning is significant in type II (down-bending) galaxy outer disks.
- Scattering contributes to type III (up-bending) galaxy outer disks.
- Type I (pure exponential) galaxies show little evidence of stellar migration.

## Abstract

Stellar migration, whether due to trapping by transient spirals (churning), or to scattering by non-axisymmetric perturbations, has been proposed to explain the presence of stars in outer disks. After a review of the basic theory, we present compelling, but not yet conclusive, evidence that churning has been important in the outer disks of galaxies with type II (down-bending) profiles, while scattering has produced the outer disks of type III (up-bending) galaxies. In contrast, field galaxies with type I (pure exponential) profiles appear to not have experienced substantial migration. We conclude by suggesting work that would improve our understanding of the origin of outer disks.