Ages of singles versus multis: Predictions for dynamical sculpting over Gyr in the Kepler sample

The sample of Kepler multis has illuminated the orbital architectures of exoplanetary systems around Sun-like stars — architectures that may be shaped mostly by formation conditions, be continually sculpted by ongoing dynamical processes, or both. As more studies place planet occurrence within a galactic context, evidence has emerged for variable planet multiplicity over time: specifically, that host stars to multiple-transiting systems are younger by several Gyr than hosts to singles or to field stars. Hypothetically, longer-timescale (> 1 Gyr) dynamical sculpting could produce this observed effect. We investigate whether there exists a dynamical sculpting law which, when operative on a large scale, (1) reproduces the observed Gyr offset between singles and multis in the Kepler sample while also (2) replicating the overall transit multiplicity observables from the mission. We employ a forward modeling framework in which we generate synthetic planetary systems, according to a prescribed sculpting speed and timescale, around the FGK dwarfs studied by Kepler. We first perform an injection-and-recovery analysis to measure our sensitivity to a suite of sculpting models, before identifying which models are consistent with the mission’s transit yield. Finally, we assess whether any law from this family of models produces the observed Gyr age offset.