OSSOS. XXI. Collision Probabilities in the Edgeworth-Kuiper Belt

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 for a collisional outcome (e.g., disruption and scattering of fragments, or formation of a crater, as both processes are related to the impact energy). We utilize an improved and debiased model of the trans-Neptunian object (TNO) region from the "Outer Solar System Origins Survey" (OSSOS). It provides a well-defined model of TNO orbital distribution, based on multiple opposition observations of more than 1000 bodies. 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 Öpik's approach, as revised and modified by Wetherill for noncircular 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 ∼ 20-200 au and V_I ∼ 0.1 km s^-1 to as high as V_I ∼ 9 km s^-1, most of the collisions are likely to happen at low relative velocities V_I < 1 km s^-1 and are dominated by the main classical belt.