Inferring the source parameters of hyperbolic binary black hole encounters with RIFT

Binary black hole systems with unbound orbits can produce a diverse array of gravitational wave signals with rich morphology. This parameter space encompasses both hyperbolic orbit scattering events and dynamical captures, including zoom-whirl orbits with multiple flybys and direct plunge mergers. These signals challenge traditional parameter estimation infrastructure, which is largely optimized for quasicircular inspiral binaries. In this work we discuss the adaptation of the Rapid Iterative FiTting (RIFT) algorithm to this problem using the TEOBResumS waveform model which can simulate generic orbits. We present results from an injection study focused on scatter events, covering a selection of mass ratios and aligned-spin configurations. Our analysis demonstrates that RIFT accurately recovers the mass and hyperbolic orbit parameters: the system energy and angular momentum as defined at a fiducial initial separation. We additionally discuss the challenges in inferring spin that arise due to both its low impact on the waveforms and degeneracy in the associated parameter space.