# Kuiper belt: formation and evolution

## TL;DR

This chapter reviews models of Kuiper belt object formation and evolution, emphasizing the compatibility of observed properties with streaming instability and giant planet instability theories, and explores their connections to other small body populations.

## Contribution

It provides a comprehensive synthesis of accretion, dynamical, and collisional models for the Kuiper belt, integrating recent developments and establishing links to related populations.

## Key findings

- The observed KBO properties are compatible with streaming instability models.
- The dynamical structure of KBOs can be explained by giant planet instability.
- The size distribution below 100 km is likely shaped by collisional equilibrium.

## Abstract

This chapter reviews accretion models for Kuiper belt objects (KBOs), discussing in particular the compatibility of the observed properties of the KBO population with the streaming instability paradigm. Then it discusses how the dynamical structure of the KBO population, including the formation of its 5 sub-components (cold, hot, resonant, scattered and fossilized), can be quantitatively understood in the framewok of the giant planet instability. We also establish the connections between the KBO population and the Trojans of Jupiter and Neptune, the irregular satellites of all giant planets, the Oort cloud and the D-type main belt asteroids. Finally, we discuss the collisional evolution of the KBO population, arguing that the current size-frequency distribution below 100~km in size has been achieved as a collisional equilibrium in a few tens of My inside the original massive trans-Neptunain disk, possibly with the exception of the cold population sub-component.