The Centaurs are a class of objects on highly chaotic, giant planet-crossing orbits. They are fed into the giant planet region due to interactions with Neptune and have dynamical lifetimes ranging from 1–100 Myr. They represent a class of intermediate bodies, with colour distributions similar to smaller Kuiper belt objects (KBOs), and sizes more typical of Jupiter family comets (JFCs), lying almost entirely beneath the observed “knee” of the known absolute H magnitude distribution. They therefore are assumed to be an intermediate population, evolving inwards into the Solar System. Understanding the diverse nature of these bodies can therefore help us understand both present-day and past Solar System evolution mechanisms.
To date there are ~100 known Centaurs. Coming online at the Vera C. Rubin Observatory in late 2025, the Legacy Survey of Space and Time (LSST) will catalogue an order of magnitude more Centaurs over its decade-long observational baseline, providing the opportunity for dedicated follow-up characterisation studies. Thus it is important to understand what will be detectable within LSST's observational biases. Sorcha is an open source, modular Solar System survey simulator, with the purpose of simulating LSST detections of all small body populations. By using an inbuilt orbit integrator combined with the most up-to-date LSST pointing database, Sorcha can return potential LSST detections of an input population.
In this work, we use the best dynamical and size distribution estimates for the Centaurs to date, calibrated to the OSSOS survey, in order to use Sorcha to predict the number of Centaur discoveries within LSST. We provide the first robust estimates of Centaur detections over the first few years within LSST, and look at the implications that the uncertainties in our colour distribution will have on the discovery rate, detectability of phase curves, cometary activity searches, and any opportunities for follow-up lightcurve studies.