Collision Probabilities in the Edgeworth-Kuiper belt

TL;DR

This study calculates collision probabilities and speeds among trans-Neptunian objects using an improved orbital model, revealing most collisions occur at low velocities within the classical belt over a wide range of distances.

Contribution

It provides the first detailed collision probability and speed calculations for various TNO populations based on an updated, de-biased orbital distribution model from OSSOS.

Findings

Collisions are possible between 20-200 AU with speeds up to 9 km/s.

Most collisions occur at low velocities below 1 km/s.

The main classical belt dominates the collision activity.

Abstract

Here, we present results on the intrinsic collision probabilities, $ P_I$, and range of collision speeds, $V_I$, as a function of the heliocentric distance, $r$, in the trans-Neptunian region. The collision speed is one of the parameters, that serves as a proxy to a collisional outcome e.g., complete disruption and scattering of fragments, or formation of crater, where both processes are directly related to the impact energy. We utilize an improved and de-biased model of the trans-Neptunian object (TNO) region from the "Outer Solar System Origins Survey" (OSSOS). It provides a well-defined orbital distribution model of TNOs, based on multiple opposition observations of more than 1000 bodies. In this work we compute collisional probabilities for the OSSOS models of the main classical, resonant, detached+outer and scattering TNO populations. The intrinsic collision probabilities and collision speeds are computed using the \"{O}pik's approach, as revised and modified by Wetherill for non-circular and inclined orbits. The calculations are carried out for each of the dynamical TNO groups, allowing for inter-population collisions as well as collisions within each TNO population, resulting in 28 combinations in total. Our results indicate that collisions in the trans-Neptunian region are possible over a wide range in ($r, V_I$) phase space. Although collisions are calculated to happen within $r\sim 20 - 200$~AU and $V_I \sim 0.1$~km/s to as high as $V_I\sim9$~km/s, most of the collisions are likely to happen at low relative velocities $V_I<1$~km/s and are dominated by the main classical belt.