Observational Constraints on Dynamical Sculpting Timescales From Kepler Demographics

The transit yield of the Kepler mission has provided rich constraints on the demographics of exoplanets around FGK dwarfs. Transit multiplicity, among other observables, provides key insights into planetary orbital architectures. Whether systems are largely unchanged since birth — or evolve dynamically over long timescales — is encoded in transit multiplicity as a function of stellar age. We describe an investigation in which we fold stellar age information into planetary system forward modeling in order to compare observations against model predictions for a range of dynamical sculpting laws. Based upon our findings, we comment on which dynamical timescales (the speed at which dynamical sculpting occurs and the duration of sculpting before it ceases) and formation conditions (the fraction of systems that are initially dynamically cool and the fraction of planet-hosting systems) are consistent with the Kepler data. The constraints we can place on dynamical timescales for FGK systems are useful both scientifically and practically. First, they inform our understanding of the relationship between common planetary dynamical timescales and life’s evolutionary timescales. Second, if there exists little evidence of dynamical sculpting at timescales longer than 1 Gyr, this may place an upper bound on integration times for resource-intensive dynamical simulations.