Collisional Fragmentation Support in TRACE

Abstract We present improved collision support for TRACE , a state-of-the-art hybrid integrator in REBOUND . TRACE now supports collisional fragmentation and can handle both removing and adding particles mid-timestep. We describe the back-end logic implemented for robust collision support, and compare TRACE ’s performance to other integrators including MERCURIUS on a large- N protoplanetary disk simulation with various collision prescriptions, a system which TRACE previously could not handle. TRACE matches the behavior of these integrators, while offering potentially vast speedups of over 70×. All updates described in this Note are available with the most recent public release of REBOUND .