Collision Probabilities in the Edgeworth-Kuiper Belt

We present results on the intrinsic collision probabilities, P_I, and range of collision speeds, V_i, as a function of the heliocentric distance, in the Edgeworth-Kuiper belt (EKB). The collision speed V_I is one of the parameters, which serves as a proxy of a collisional outcome e.g., complete disruption and scattering of fragments, or formation of crater, where both processes are directly related to impactor's energy. We utilize an improved and de-biased model of the trans-Neptunian object (TNO) region from the so called "Ensemble", consisting of the "Canada-France Eclptic Plane Survey", the Mike Alexandersen's pathfinding study and more recently the "Outer Solar System Origin Survey". This survey provides well-defined orbital distribution model of the Kuiper belt objects, based on multiple opposition observations of over 1000 bodies. We divide the main classical belt into two dynamically distinct subgroups: (i) Cold with inclinations i<5 deg and (ii) Hot with i > 5 deg. We consider seven different "resonant" populations, currently in mean motion resonance (MMR) with Neptune: 4:3, 3:2, 5:3, 7:4, 2:1, 7:3 and 5:2 MMR, which, when considering the collisional probabilities we consider as three groups: (i) Inner resonances - interior to and including the 3:2 MMR, (ii) Main resonances - objects between but excluding 3:2 and 2:1 MMR and (iii) Outer resonances - beyond and including the 2:1 MMR. The detached and outer classical belt are grouped into a single orbital population when considering the collision probabilities, we refer to this component as the "Detached" EKB. The intrinsic collision probabilities P_i and collision speeds are computed using the method described in Wetherill (1967) and modified by Greenstreet et al. (2015).The calculations are carried out for each of the dynamical TNO groups, allowing for inter-population collisions as well as collisions within each KBO population.We find that collisions in the EKB are mostly constrained to the main classical belt with corresponding impact speeds V_I < 1 km/s, a result which raises the question if these impacts are destructive or just crater forming.